White opals, on the other hand, are almost creamy and sometimes called milk opal. Because they are white, they do not show the inner color as well as black opals and are generally only bought as white opals. However, some color flashing can still be seen in an excellent quality opal gemstone. These can be purchased relatively cheaply, although really high-quality ones can cost you a few hundred or a thousand dollars.

1. How to tell one opal from another
How do you tell one opal from another? What is the difference between different opals? And why
is it important to do so?
Opals are unique in that they are not gems or like diamonds or rubies, they are made of a
completely different material and like many other gemstones have their differences which can
add up to thousands of dollars so it is wise to understand. opals and the differences between
them.
Some of the more common opals available are:
Black opal
White opal
Boulder Opal
Crystal opal
Fire Opal Ring
Matrix Opal
Black opal has a dark body tone that causes a brightness of color that is incomparable to other
types of opal. Black opals are only mined at Lightning Ridge in New South Wales, Australia and
are considered very rare and are the most expensive of all opal jewelry.
White opals, on the other hand, are almost creamy and sometimes called milk opal. Because they
are white, they do not show the inner color as well as black opals and are generally only bought
as white opals. However, some color flashing can still be seen in an excellent quality opal
gemstone. These can be purchased relatively cheaply, although really high-quality ones can cost
you a few hundred or a thousand dollars.
Boulder Opals are different again. They come from the great iron borders, hence the name,
underground.
A crystal opal can be the same as above, but has a transparent or semi-transparent body tone,
which means you can see through the stone. Crystal opal can have a dark or light body tone,
hence "black crystal opal" and "white crystal opal"
Fire opal is an American term and describes any opal that has a significant amount of red
coloring. Red is the rarest color in opals, so they are quite valuable. Often confused with
"Mexican Fire Opal", which is again different and displays an orange instead of red coloration.

2. Matrix opal is where opal occurs as a network of veins or filling cavities or between grains of the
host rock. The matrix contains rare opal silica as a pore space filler in silty clay or ironstone.
matrix opal shows a fine needle-like color in its natural state. also very rare.