This document provides an overview of a short course on gemology taught at Somaville University. It defines gemology as the science dealing with natural and artificial gemstone materials. It then discusses what constitutes a gemstone and provides details on hardness, clarity, treatments, and sources for several precious and semi-precious gemstones including diamond, ruby, sapphire, emerald, topaz, zircon, and spinel. Requirements for good quality gemstones are outlined. Mohs scale of hardness is also explained.
Gemmology is a vast subject to learn about all the Gemstones, their properties, occurrences, geographical location, geometrical structure or formations, various colour shades, transparency to opaque, sheen & luster, cuts & shapes, carat & cost, testing through various instruments & devices for their Real, synthetics or simulants.
Gemology is the scientific study of gemstones. Its practitioners, called gemologists, are experts in identifying gems and grading their purity, as well as authorities in the art of jewelry creation and stone setting.
A List Of Precious And Semi Precious Gemstones9gemeu
There are so many types of gemstones available today. We have created a comprehensive list of gemstones to guide you and help to find the perfect gemstone. others to be semi-precious, more are considered fine or ornamental. Differences apply. What stones are considered precious and which are those considered semi precious
Developed by Scott B Britton, GIA Graduate Gemologist, Gemology 101: Principles and Practices is a comprehensive PowerPoint presentation designed for jewelry professionals, students, and gem connoisseurs and collectors alike that explains in detail the basics of gemology and how to use the information to identify unknown gems.
Gemmology is a vast subject to learn about all the Gemstones, their properties, occurrences, geographical location, geometrical structure or formations, various colour shades, transparency to opaque, sheen & luster, cuts & shapes, carat & cost, testing through various instruments & devices for their Real, synthetics or simulants.
Gemology is the scientific study of gemstones. Its practitioners, called gemologists, are experts in identifying gems and grading their purity, as well as authorities in the art of jewelry creation and stone setting.
A List Of Precious And Semi Precious Gemstones9gemeu
There are so many types of gemstones available today. We have created a comprehensive list of gemstones to guide you and help to find the perfect gemstone. others to be semi-precious, more are considered fine or ornamental. Differences apply. What stones are considered precious and which are those considered semi precious
Developed by Scott B Britton, GIA Graduate Gemologist, Gemology 101: Principles and Practices is a comprehensive PowerPoint presentation designed for jewelry professionals, students, and gem connoisseurs and collectors alike that explains in detail the basics of gemology and how to use the information to identify unknown gems.
THE DISTRIBUTION OF IGNEOUS ROCKS IN SPACE AND TIME
CONSANGUINITY-The term consanguinity (Iddings) is used to indicate the fact that certain groups of igneous rocks, the members of which are associated in space and time, possess a community of character or family likeness which is expressed in their chemical, mineralogical, textural, and geological features. While in chemical composition consanguineous series or suites may range from acid to ultrabasic types, some mineral and chemical characters are constant, i.e. are common to practically all members; while other characters are serial, that is to say, they show regular variation throughout the series. Thus, in some suites, a constant character is oversaturation with silica, which causes free silica to appear in quite basic members. A serial character may be afforded by the regular variation of the alkalis, or of ferrous iron oxide and magnesia throughout the suite. Some series may be characterised throughout by a peculiar mineralogical feature, such as the occurrence of anorthoclase, as in certain Norwegian, East Mrican, and Antarctic suites. Consanguinity in an igneous series leads to the hypothesis that the assemblage has been derived by some process of differentiation from a common initial magma, from a number of closely related magmas.
Geological sample preparation is a vital stage in the analytical process, given the highly variable nature of mineral samples. The purpose of sample preparation is the production of homogeneous sub-sample, representative of the material submitted to the laboratory.
Gemology/Gemmology in forensic science .pptxBhanu Yadav
In this presentation, I have aimed to describe various physical and chemical properties of gemstones that are of use in traditional gemstone studies as well as in the aspects of forensic science.
Beginning from a brief history of how gemology or gemmology evolved from a hobby into a full fledged science and ending at X-ray diffraction studies (brief)
Gold is a transitional metal. In its purest form have reddish yellow color, soft, malleable, and ductile metal.
Atomic number : 79
Atomic mass : 196.9 u
Density : 19.32 g/cm3
Melting point : 1,064 °C
Boiling point : 2,700 °C
Founded in different form associated with different rock type in different tectonic setting.
Discovered from earlier time and used for multi purposes.
Formation of gold
The saying among prospectors that "gold is where you find it" suggests its occurrence is unpredictable, but there is some certain geological environments for the formation.
Because gold is very stable over a range of conditions, it is very widespread in the earth’s crust.
Gold dissolved in warm to hot salty water, the fluids are generated in huge volumes deep in the Earth’s crust as water-bearing minerals dehydrate during metamorphism.
Any gold present in the rocks being heated and squeezed is sweated out and goes into solution as complex ions.
In this form, dissolved gold, along with other elements such as silicon, iron and sulphur, migrates wherever fractures in the rocks allow the fluids to pass.
The direction is generally upwards, to cooler regions at lower pressures nearer the Earth’s surface.
Gold eventually becomes insoluble and begins to crystallize, most often enveloped by quartz.
The association of gold and quartz vein forms one of the most common types of "primary gold deposits".
India
In India, gold mineralization of economic importance is mainly restricted to Archean greenstone terranes of the Dharwar Craton (DC).
The eastern block of the DC has a high favorability for hosting major gold deposits such as Kolar, Hutti, and Ramagiri, whereas the western block hosts only a few smaller deposits such as Gadag, Ajjahanahalli, and Kempinkote.
Gold also discoverrd by GSI in the Singbhum Craton, Aravalli Craton, Bastar Craton and Southern Granulite Terrain (SGT).
India is the second-largest consumer of gold after China.
India currently holds about 558 tones of gold, representing 6.6% of its reserves, (World Gold Council, October 2016).
Kolar Gold Field, Hutti Gold Field and Ramgiri Gold Field are the most important gold fields.
Gold Demand and Use
The largest source of demand is the jewelry industry Gold’s workability, unique beauty, and universal appeal make this rare precious metal the favorite of jewelers all over the world.
Besides jewelry, gold has many applications in a variety of industries including aerospace, medicine, dentistry, and electronics for the manufacture of computers, telephones, televisions...
The third source of gold demand is governments and central banks that buy gold to increase their official reserves.
Private investors there are private investors. Depending upon market circumstances, the investment component of demand can vary substantially from year to year.
Name: Probably used in the mineralogical sense by 1706 and originally "smicka" and from the Latin micare - to flash or glisten in allusion to the material's appearance. Isinglass predates the use of mica as a mineral term and known from at least 1535, but isinglass also referred to the matter from the sturgeon fish that also had pearly flakes from the scales.
Mica is widely distributed and occurs in igneous, metamorphic and sedimentary regimes. Mica group represents 34 phyllosilicate minerals that exhibits a layered or platy structure. Commercially important mica minerals are muscovite (potash or white mica) and phlogopite (magnesium or amber mica). Granitic pegmatites are the source of muscovite sheet, while phlogopite is found in areas of metamorphosed sedimentary rocks into which pegmatite rich granite rocks have been intruded. It possesses highly perfect basal cleavage due to which it can easily and accurately split into very thin sheets or films of any specified thickness. It has a unique combination of elasticity, toughness, flexibility and transparency. It possesses resistance to heat and sudden change in temperature and high dielectric strength. It is chemically inert, stable and does not absorb water.
THE DISTRIBUTION OF IGNEOUS ROCKS IN SPACE AND TIME
CONSANGUINITY-The term consanguinity (Iddings) is used to indicate the fact that certain groups of igneous rocks, the members of which are associated in space and time, possess a community of character or family likeness which is expressed in their chemical, mineralogical, textural, and geological features. While in chemical composition consanguineous series or suites may range from acid to ultrabasic types, some mineral and chemical characters are constant, i.e. are common to practically all members; while other characters are serial, that is to say, they show regular variation throughout the series. Thus, in some suites, a constant character is oversaturation with silica, which causes free silica to appear in quite basic members. A serial character may be afforded by the regular variation of the alkalis, or of ferrous iron oxide and magnesia throughout the suite. Some series may be characterised throughout by a peculiar mineralogical feature, such as the occurrence of anorthoclase, as in certain Norwegian, East Mrican, and Antarctic suites. Consanguinity in an igneous series leads to the hypothesis that the assemblage has been derived by some process of differentiation from a common initial magma, from a number of closely related magmas.
Geological sample preparation is a vital stage in the analytical process, given the highly variable nature of mineral samples. The purpose of sample preparation is the production of homogeneous sub-sample, representative of the material submitted to the laboratory.
Gemology/Gemmology in forensic science .pptxBhanu Yadav
In this presentation, I have aimed to describe various physical and chemical properties of gemstones that are of use in traditional gemstone studies as well as in the aspects of forensic science.
Beginning from a brief history of how gemology or gemmology evolved from a hobby into a full fledged science and ending at X-ray diffraction studies (brief)
Gold is a transitional metal. In its purest form have reddish yellow color, soft, malleable, and ductile metal.
Atomic number : 79
Atomic mass : 196.9 u
Density : 19.32 g/cm3
Melting point : 1,064 °C
Boiling point : 2,700 °C
Founded in different form associated with different rock type in different tectonic setting.
Discovered from earlier time and used for multi purposes.
Formation of gold
The saying among prospectors that "gold is where you find it" suggests its occurrence is unpredictable, but there is some certain geological environments for the formation.
Because gold is very stable over a range of conditions, it is very widespread in the earth’s crust.
Gold dissolved in warm to hot salty water, the fluids are generated in huge volumes deep in the Earth’s crust as water-bearing minerals dehydrate during metamorphism.
Any gold present in the rocks being heated and squeezed is sweated out and goes into solution as complex ions.
In this form, dissolved gold, along with other elements such as silicon, iron and sulphur, migrates wherever fractures in the rocks allow the fluids to pass.
The direction is generally upwards, to cooler regions at lower pressures nearer the Earth’s surface.
Gold eventually becomes insoluble and begins to crystallize, most often enveloped by quartz.
The association of gold and quartz vein forms one of the most common types of "primary gold deposits".
India
In India, gold mineralization of economic importance is mainly restricted to Archean greenstone terranes of the Dharwar Craton (DC).
The eastern block of the DC has a high favorability for hosting major gold deposits such as Kolar, Hutti, and Ramagiri, whereas the western block hosts only a few smaller deposits such as Gadag, Ajjahanahalli, and Kempinkote.
Gold also discoverrd by GSI in the Singbhum Craton, Aravalli Craton, Bastar Craton and Southern Granulite Terrain (SGT).
India is the second-largest consumer of gold after China.
India currently holds about 558 tones of gold, representing 6.6% of its reserves, (World Gold Council, October 2016).
Kolar Gold Field, Hutti Gold Field and Ramgiri Gold Field are the most important gold fields.
Gold Demand and Use
The largest source of demand is the jewelry industry Gold’s workability, unique beauty, and universal appeal make this rare precious metal the favorite of jewelers all over the world.
Besides jewelry, gold has many applications in a variety of industries including aerospace, medicine, dentistry, and electronics for the manufacture of computers, telephones, televisions...
The third source of gold demand is governments and central banks that buy gold to increase their official reserves.
Private investors there are private investors. Depending upon market circumstances, the investment component of demand can vary substantially from year to year.
Name: Probably used in the mineralogical sense by 1706 and originally "smicka" and from the Latin micare - to flash or glisten in allusion to the material's appearance. Isinglass predates the use of mica as a mineral term and known from at least 1535, but isinglass also referred to the matter from the sturgeon fish that also had pearly flakes from the scales.
Mica is widely distributed and occurs in igneous, metamorphic and sedimentary regimes. Mica group represents 34 phyllosilicate minerals that exhibits a layered or platy structure. Commercially important mica minerals are muscovite (potash or white mica) and phlogopite (magnesium or amber mica). Granitic pegmatites are the source of muscovite sheet, while phlogopite is found in areas of metamorphosed sedimentary rocks into which pegmatite rich granite rocks have been intruded. It possesses highly perfect basal cleavage due to which it can easily and accurately split into very thin sheets or films of any specified thickness. It has a unique combination of elasticity, toughness, flexibility and transparency. It possesses resistance to heat and sudden change in temperature and high dielectric strength. It is chemically inert, stable and does not absorb water.
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Precious gemstones such as sapphire, ruby, and emerald are among the most prized. Online gemstones offer precious gemstone at discount price. Buy Precious gemstones here.
Opal gemstone build a number of the foremost stunning items of jewellery accessible. the majority area unit acquainted with diamonds, rubies, and pearls. but there area unit several others that attract the attention because of their exquisite beauty, however they're less standard. Keep reading for a quick description of a number of the foremost eye-appealing gems within the world.
5 Common Gemstones Used In Jewellery.pptxMaliha Laiq
Precious gems, are very rare and do not occur frequently in the Earth’s crust. Their value is not only because of their beauty but also because of their rarity.
Semi-precious gems, are more common and are also used for jewellery and other ornamental purposes.
Uncut gems, are not used for other purposes and are sold as uncut stones.
Gemstones are usually cut into cabochons or faceted gems. Cabochons are stones that have been polished and have only one flat polished face. Faceted gems have many polished faces, or facets, and are usually cut from a flat-bottomed rock crystal (rock crystal is also known as natural transparent quartz since it is colourless).
Minerals resources including toumaline, sapphire and peridot.
sapphire is a precious gemstone used in jwellery. paridot and tourmaline are semi-precious gemstones. they are less expensive than sapphire.
A ruby is a pink to blood-red colored gemstone, a variety of the mineral corundum (aluminium oxide)<a href="https://www.chordiajewels.com/categories/ruby"Ruby</a>
Also called the Oct Birthstone and therefore the fourteenth and eighteenth day of remembrance stone, the opaque gem is one in every of nature's greatest splendors. the colours will vary in any color of the rainbow. the foremost placing quality of opaque gem is its ability to refract and replicate specific wavelengths of sunshine. The interaction of various wavelengths of sunshine offers opaque gem its distinctive visual attractiveness, and makes it one in every of the foremost sought-after gemstones within the world. it's positively one in every of the world's most lovely and precious opals nickname. The word opaque gem derives from varied languages: in Indo-Aryan upala, which means "precious stone", in Latin, the opalus and Greek opallios, each which means "to see color change".
Precious blue sapphire mining, origin and properties9gemeu
Blue Sapphire symbolizes wisdom, good fortune, happiness, holiness for royals. It is powerful stone for enhancing or increasing mental clarity and spiritual power. It has many different colors from light blue to dark blue but cornflower is the most valuable color among all. It is birthstone of month “September”.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
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Monitor common gases, weather parameters, particulates.
The increased availability of biomedical data, particularly in the public domain, offers the opportunity to better understand human health and to develop effective therapeutics for a wide range of unmet medical needs. However, data scientists remain stymied by the fact that data remain hard to find and to productively reuse because data and their metadata i) are wholly inaccessible, ii) are in non-standard or incompatible representations, iii) do not conform to community standards, and iv) have unclear or highly restricted terms and conditions that preclude legitimate reuse. These limitations require a rethink on data can be made machine and AI-ready - the key motivation behind the FAIR Guiding Principles. Concurrently, while recent efforts have explored the use of deep learning to fuse disparate data into predictive models for a wide range of biomedical applications, these models often fail even when the correct answer is already known, and fail to explain individual predictions in terms that data scientists can appreciate. These limitations suggest that new methods to produce practical artificial intelligence are still needed.
In this talk, I will discuss our work in (1) building an integrative knowledge infrastructure to prepare FAIR and "AI-ready" data and services along with (2) neurosymbolic AI methods to improve the quality of predictions and to generate plausible explanations. Attention is given to standards, platforms, and methods to wrangle knowledge into simple, but effective semantic and latent representations, and to make these available into standards-compliant and discoverable interfaces that can be used in model building, validation, and explanation. Our work, and those of others in the field, creates a baseline for building trustworthy and easy to deploy AI models in biomedicine.
Bio
Dr. Michel Dumontier is the Distinguished Professor of Data Science at Maastricht University, founder and executive director of the Institute of Data Science, and co-founder of the FAIR (Findable, Accessible, Interoperable and Reusable) data principles. His research explores socio-technological approaches for responsible discovery science, which includes collaborative multi-modal knowledge graphs, privacy-preserving distributed data mining, and AI methods for drug discovery and personalized medicine. His work is supported through the Dutch National Research Agenda, the Netherlands Organisation for Scientific Research, Horizon Europe, the European Open Science Cloud, the US National Institutes of Health, and a Marie-Curie Innovative Training Network. He is the editor-in-chief for the journal Data Science and is internationally recognized for his contributions in bioinformatics, biomedical informatics, and semantic technologies including ontologies and linked data.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
2. What is gemology?
Gemology or gemmology is the
science dealing with natural and
artificial gemstone materials. It is
considered a geoscience and a branch
of mineralogy. Some jewelers are
academically trained gemologists and
are qualified to identify and evaluate
gems.
3. What is gemstone?
A gemstone is the naturally
occurring crystalline form of a
mineral, which is desirable for its
beauty, valuable in its rarity and
durable enough to be enjoyed for
generations.
4. A gemstone or gem (also called a fine gem, jewel, or a
precious or semi-precious stone) is a piece of mineral
crystal, which, in cut and polished form, is used to make
jewelry or other adornments. However, certain rocks (such
as lapis lazuli) or organic materials that are not minerals
(such as amber or jet), are also used for jewelry, and are
therefore often considered being gemstones as well. Most
gemstones are hard, but some soft minerals are used in
jewelry because of their luster or other physical properties
that have aesthetic value. Rarity is another characteristic that
lends value to a gemstone. Apart from jewelry, from earliest
antiquity engraved gems and hard stone carvings, such as
cups, were major luxury art forms. A gem maker is called a
lapidary or gem cutter; a diamond worker is a diamantaire.
5. What is the Hardness of Mohs Scale?
The Mohs scale of mineral hardness is a qualitative ordinal
scale that characterizes the scratch resistance of various minerals
through the ability of a harder material to scratch a softer
material. It was created in 1812 by the German geologist and
mineralogist Friedrich Mohs and is one of several definitions of
hardness in materials science, some of which are more
quantitative.The method of comparing hardness by seeing which
minerals can visibly scratch others, however, is of great
antiquity, having been mentioned by Theophrastus in his treatise
On Stones, c. 300 BC, followed by Pliny the Elder in his
Naturalis Historia, c. 77 AD. While greatly facilitating the
identification of minerals in the field, the Mohs scale does not
show how well hard materials perform in an industrial setting.
Moh’s Scale of the precious and semi-precious gemstones
7. Requirements of Good Quality Gemstone
•Transparent
To be applicable to pass through light wholly, this makes to
the stone very beauty.
•No Cracks
The crack is to get inside the stone in tears that causes to
uncut to the stone for the reason of this cracks in it.
•No Inclusion and no Rutile
In mineralogy, an inclusion is any material that is trapped
inside a mineral during its formation. In gemology, an
inclusion is a characteristic enclosed within a gemstone, or
reaching its surface from the interior. According to Hutton's
law of inclusions, fragments included in a host rock are older
than the host rock itself.
9. •DIAMOND
Hardness: 10 Compositions: Carbons
Diamond is the hardest mineral on Earth , this combined with its
exceptional luster and brilliant fire , has made it the most highly prized of all
gems ,pure , colorless diamond is the most popular, but other varieties –
from yellow and brown to green, blue, pink, red, grey, and black – are also
found, depending on the impurities present. Because of the uniform
arrangement of their constituent carbon atoms, diamond crystals are well –
formed – usually octahedral with rounded edges and slightly convex faces
their perfect cleavage facilitates the early stages of fashioning but they can
only be polished by other diamonds,
•OCCURRENCE Diamond forms at high temperatures and pressures 80km
(50 miles) more underground most Diamond came from second sources ,
such as rivers and gravels, however , since discovery of diamond in
kimberlitic rock in south Africa (around 1870),its extraction has involved
processing vast quantities of rock, Australia is the main producer today:
other localities include Ghana Sierra Leone, Zaire, Botswana, Namibia, the
former USSR, the USA, and Brazil,
10. Diamond Clarity
Key Points
•Clarity is a measure of the number and size of the tiny imperfections
that occur in almost all diamonds.
•Many of these imperfections are microscopic, and do not affect a
diamond's beauty in any discernible way.
Much is made of a diamond's clarity, but of the Four Cs, it is the
easiest to understand, and, according to many experts, generally has
the least impact on a diamond's appearance. Clarity simply refers to
the tiny, natural imperfections that occur in all but the finest
diamonds. Gemologists refer to these imperfections by a variety of
technical names, including blemishes and inclusions, among others.
Diamonds with the least and smallest imperfections receive the
highest clarity grades. Because these imperfections tend to be
microscopic, they do not generally affect a diamond's beauty in any
discernible way.
11. Diamond Clarity
Flawless, Internally Flawless: No internal or external
imperfections. Internally Flawless: No internal
imperfections. Very rare.
Very, Very Slightly Included: Very difficult to see imperfections
under 10x magnification. An excellent quality diamond.'
VVS1, VVS2
FL, IF
12. Very Slightly Included: Imperfections are not typically visible to the
unaided eye. Less expensive than the VVS1 or VVS2 grades.'
Slightly Included: Imperfections are visible under 10x
magnification, and may be visible with the unaided eye. A good
diamond value.'
SI1, SI2
VS1, VS2
13. I1
Included: Blue Nile offers a limited selection of jewelry with diamonds of I1 grade
clarity. This grade of diamonds will have minor inclusions that may be visible to
the unaided eye.'
I2, I3
What Clarity Grade Is Right For Me?
•Select an "eye-clean" diamond - one that has no imperfections visible to the
unaided-eye through the crown. An excellent value, diamonds of this clarity
are much less expensive than flawless (FL) or internally flawless (IF)
diamonds, which are extremely rare and command higher prices.
•Frequently, imperfections in diamonds graded slightly included (SI) are not
visible to the unaided eye, making them an excellent value. If you're
considering a diamond with an SI clarity grade, call to speak to a diamond
and jewelry consultant who will review the diamond to ensure the
imperfections are not visible to the unaided eye.
14. •RUBY
Hardness: 8 Composition: Aluminium oxide
Ruby the given to red, gem-quality corundum – is
one of the best gemstones for jewellery settings.
Rubies may be any shade of red, from pinkish to
purplish or brownish red, depending on the
chromium and iron content of the stone
•OCCURRENCE Worldwide in igneous and
metamorphic rocks, or as water worm pebbles in
alluvial deposits The finest stones come from
Burma
15. •SAPPHIRE
Hardness 9 Composition Aluminium oxide
All gem quality corundum that is not red is called sapphire, yet this
name is popularly associated with the colour blue, but most
valuable is the clear, deep blue some stones called “colour”-change
sapphire “,exhibit different shades of blue in artificial and natural
light.
•OCCURRENCE Good quality sapphire is found in Burma, Sri
lank, and India, The best Indian sapphire is cornflower blue,
and found in Kashmir either in pegmatite’s or as wter worm
pebbles in alluvial deposits sapphire from Thailand, Australia,
and Nigeria is dark blue, and may appear nearly Black
Montana (USA) producers sapphire of an attractive metallic
blue Other localities include Cambodia, Brazil, Kenya, Malawi,
and Colombia,
16. •EMERALD
Hardness: 8 Composition: Beryllium Chromium Vanadium
Aluminium Silicate
Emerald derives its beautiful green colour from the presence of
chromium and vanadium Emeralds are rarely flawless, so stones
are often oiled to fill and disguise cracks, hide flaws and enhance
colour to minimize the loss of material, the step cut (or “emerald-
cut”, as it is known) is commonly used, but ancient engravings are
known, cameos, intaglios, and beads can make the best of a flawed
stone.
•OCCURRENCE found in granites, pegmatite’s, and schist as
well as alluvial deposits the finest emerald are from Colombia,
Other sources are Australia India Austria, Brazil, South Africa,
Egypt , USA, Norway, Pakistan, and Zimbabwe
17. •TOPAZ
Hardness: 8 Composition: Alluminium Flouro hydroxy ilicate
Topaz occurs in range of deferent colours deep golden yellow
topaz (sometimes called sherry topaz) and pink topaz are the
most valuable: blue and green stones are also popular. Natural
pink stones are rare most pink topaz is heat-treated yellow
material
•ZIRCON
Hardness 8 Composition Zirconium silicate
Zircon is almost famous for its colour less stones which
closely resemble diamond and have been used both
intentionally and mistakenly in their place
•OCCURRENCE Gem quality crystals are usually found as
pebbles in alluvial deposits
18. •SPINEL
Hardness: 8 Compositions: Magnesium Allumnium Oxide
SPINEL is found in a wide range of colours due to the presence of
various impurities andis transparent to almost opaque red spinel
coloured by chromium and iron is the most popular, although for
many years it was thought to be a variety of ruby
•OCCURRENCE spinel occurs in granites and metamorphic
rocks, and is often found in association with corundum Octahedral
crystals and waterworm pebbles in a wide range of of colours are
found in the gem gravels of Burma, Srilanka and Madagascar
•REMARK synthetic spinel has been manufactured since 1910it
has been used to imitate diamond, coloured to imitate stones such
as aquamarine and zircon, blue synthetic spinel, coloured by
cobalt, has been used to imitate sapphire The name may derive
from the Latin word spina, meaning little thorn, referring to the
sharp points on the crystals,
19. •BERYL
Hardness: 8 Composition: Beryllium Aluminium Silicate
Beryl derives its beautiful multi colures from the deserted of chromium and
vanadium Beryl are rarely flawless, so stones are often oiled to fill and
disguise cracks, hide flaws and enhance colour to minimize the loss of
material, the step cut (or “emerald-cut”, as it is known) is commonly used,
but ancient engravings are known, cameos, intaglios, and beads can make the
best of a flawed stone.
•OCCURRENCE found in granites, pegmatite’s, and schist as well as
alluvial deposits the finest emerald are from Colombia, Other sources
are Australia India Austria, Brazil, South Africa, Egypt , USA, Norway,
Pakistan, and Zimbabwe
There are many types of group beryl:-
•Red Beryl
•Morganite Beryl
•Goshonite Beryl
•Aquamarine Beryl
•Beryl
•Alexandrite Beryl
20. •TOURMALINE
Hardness: 7 Composition: Complex borosilicate
Members of the tourmaline family of the minerals have the same basic
crytal structure, but occur in many colours. Rubellite (from the latin
for red) is the name given to the pink or red variety with ruby- red
stones the most highly prized. Rubellite crystals are striated, with
triangular cross-section and a rounded outline they may also occur
with a fibrous habit, and and show cat’s eye when en cabochon.
There are many types of tourmaline:-
•Rubellite Tourmaline: read tourmaline
•Elbite Tourmaline: blue tourmaline
•Indicolite Tourmaline: green tourmaline
•Watermelon Tourmaline: green and red mixed tourmaline
•Bi color Tourmaline: any two colors mixed tourmaline
•Paraiba Tourmaline: light blue tourmaline is the rarest type of
tourmaline
21. •GARNET
Hardness: 7 Composition: Magnesium Aluminium Silicate
Garnet the blood red colour of pyrope is due to its iron and chromium content, it
rarely has inclusions , but when present they are rounded crystals or have
irregular out lines ,As with all garnets, pyrope has no cleavage, and fracture is
subconchoidal to uneven
•OCCURRENCE Pyrobe is found in volcanic rock and alluvial deposits,
and may along with certain other minerals, indicate the precence of
diamond bearing rocks localities include Arizona (USA), South Africa,
Argentina , Australia, Brazil, Burma , Scotland, Switzerland, and Tanzania.
•REMARK: pyrope come from Gteek pyrops meaning burning.
There are many types of Garnet group:-
•Rhodolite Garter: dark red garnet
•Specertite Garnet: orange garnet
•Pyrobe Garnet: blood red garnet
•Almandine Garnet: dark coffee garnet
•Hessonite Garnet: dark orange garnet
•Tsavorite Garnet: green garnet is the most rarest type of garnet group
22. •QUARTZ
Hardness: 7 Composition: Silicon Dioxide
Citrine is the yellow or golden variety of quartz, The yellow coloration,
due to the presence of iron, is also responsible for the name, derived
from the word “citrus” natural citrine is usually a pale yellow but rare:
There are three types of quartz:-
•Macrocrystalline Quartz
Rock Crystal
Amethyst
Aventurine
Eisenkiesel
Rose Quartz
Tiger's, Hawk's, Cat's Eye
24. •OPAL
Hardness: 6.5 Composition: Silica (SiO2·nH2O)
Opal is a hydrated amorphous form of silica (SiO2·nH2O);
its water content may range from 3 to 21% by weight, but
is usually between 6 and 10%. Because of its amorphous
character, it is classed as a mineral oid, unlike crystalline
forms of silica, which are classed as minerals. It is
deposited at a relatively low temperature and may occur in
the fissures of almost any kind of rock, being most
commonly found with limonite, sandstone, rhyolite, marl,
and basalt. Opal is the national gemstone of Australia.
