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Beauty is another characteristic that affects the gem's price. You
can see, that your favourite gem is beautiful. How can you describe
this to others?
Beauty is color, whether it is invigorating and warm color of a ruby or
mysterious color of an emerald. Shape and cut is of a big significance
too. They can show the beauty of the stone or kill it.
Only a professional gemologist can see if there is an interesting
optical effect in the rough gem and choose the cut, that should be
individual. Transparent stones mostly have faceted cuts, but if there
is a "star" or a "cat's eye" effect then the stone must be cut as a
cabochon.
How really beautiful is your stone? You need to know what to look at,
so look at its lustre, brilliance and "fire".
Lustre is an optical effect produced by the light reflected from the
surface of a mineral. Rays of light partially pass through the stone and are
partially reflected. So, the brilliance depends on the internal nature of
the stone on one hand and on the surface and the quality of its polish on
another hand.
Look closely at your stone. How well is it polished? The surface
should be smooth and shiny. If it is, you will be able to see the most
brilliance and lustre that your stone can show.
Most transparent and translucent gems have brilliant (adamantine) and
glass (vitreous) lustre.
What lustre does your stone have? Does it have the same lustre as
glass or is it much brighter, like a diamond?
Vitreous lustre is a characteristic of a quartz, sapphire or topaz.
Adamantine lustre is a characteristic of a diamond, zircon and
demantoid (green garnet).
Resinous lustre is a lustre like that of a resin (examples: some
garnets and amber).
Pearls and moonstone has pearly lustre.
Satin-spar has silky lustre.
If there is "fire" in a stone it adds it more beauty. Move your stone
under the light. Do you see the sparkles of rainbow? Fire is especially
important for the colourless stones. Usually the gems judged by the combination of lustre and fire. A cut is chosen individually for each gem in order to enhance them. The most brilliant stones that have the best combination
of both are diamonds, zircons, garnets almandine, rubies, sapphires,
spinels and topazes.
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