Black opal is a rare and valuable form of opal that exhibits dramatic play of color effects when turned in the light. Opal forms when silica spheres of different sizes in a stone reflect and refract light, producing flashes of color. Black opal is particularly prized for highlighting these effects. Most black opals come from mines in Australia, though other sources include Mexico, Guatemala, and Honduras. An opal's value depends on its body color, dramatic color effects, and lack of flaws - a flawless black opal with bright, uniform colors can be worth more per carat than a diamond.

1. Keyword: Black Opal Ring
Landing Page: https://australianopaldirect.com/rings/black-opal-rings/
Opal - Its Fascinating History and Healing Power
The name Opal is derived from the Greek name "opallios" and from the Sanskrit "upala",
meaning "Precious Stone". It is different from most precious gems because of its non-
crystalline crystal system, or amorphous, in nature. Opal is allochromatic and comes in a
variety of colors, the most valued being black. Other forms include white (milk opal), red (fire
opal), or colorless (water opal). The most striking features of precious opal are the sheen
effects it exhibits when turned in the light, known as "play of color". This is caused by minute
spheres of silica that reflect and diffract white light. This effect is known as "opalescence".
Smaller spheres produce only blues and greens, whereas larger ones produce the whole
spectrum. Black opals highlight play of color most dramatically. Opals look very good in
simple jewelry settings and look particularly attractive, when they are set in rings.
Identification:
Opal has a hardness of 5.5 to 6.5 and specific gravity of 2.1 to 2.2 and has a low density. It
is transparent to opaque, has a vitreous, greasy, dull, or waxy luster, and leaves a white
streak. It is singly refractive, and it is porous. In this case, it is dangerous to immerse it in any
liquids other than water.
Occurrence:
One area of former Czechoslovakia formerly belonging to Hungary has been mining Opal
since Roman times and was the only source of noble Opal to Europeans. In modern times,
most opals are coming from Australia where the finest quality opals are found. Other sources
are mainly Mexico, Guatemala, Honduras, United States and Iceland.
Varieties:
There are few varieties, but mainly there are 3 varieties that are most popular in gem
business are follows: White Precious Opal, Black Precious Opal and Fire Opal and also
called common opal. Each one has its own distinctive colors and characteristics.
Value:
An opal's value depends on its body color, play of color, and soundness. There is no
comparison between the value of noble opal and that of fire opal, which is quite inexpensive
even compared with other minor gems. It is worth somewhat more when a few splashes of
color are visible inside the stone. It is valued by collectors as a curiosity but is little used in
jewelry. A black opal, free from flaws and with a uniform pattern made up of bright clear
colors, including red, may be worth more per carat than diamond. Common opals do not
exhibit play of color and, as a result, are valueless.
History and Healing Uses:

2. Opals were adored by the ancient Romans; used as an eye tonic in the Middle Ages;
celebrated by Shakespeare; and were a favorite gemstone of Queen Victoria. The most
common and popular background is milk white, it is called White Precious Opal. The stone
can be used to enhance psychic awareness as well as energizing all levels and areas of the
body, because of the rainbow of colors that is contained with it.
Simulants and Synthetics:
It was long considered impossible to imitate opal. In recent years, however, an imitation,
which, at first sight, looks deceptively similar to opal, has appeared on the market. It is called
"Slocum Stone" after its inventor. A plastic imitation has also recently come onto the market
and it is very similar to natural opal, being composed of microscopic spheres, like opal.
White opal has been manufactured synthetically by the French Company for nearly a
decade.