An interview with Nader Ayad, GG 1986, ISA 1992, (GIA) Graduate Gemologist and owner of Mission Hills Gallery (Part 2)
Is it easy to identify gems, even when they are in their rough state? Must they be polished first?
Gems can be identified in their rough state by their crystal formation, color, and specific gravity. The streak test may also be used. This observes the color of the powder seen after a mineral is scratched against a streak plate. However, this does not necessarily depend on the color of the mineral; for example, the streak of black jade is always green. A Mohs’ Hardness scale from one to ten also helps identify stones. A diamond is the hardest gemstone, with a hardness rating on ten. Still, most identification tests require polishing one side to obtain a refractive index, or RI, reading.
Is it possible to “repair” poor quality gemstones with fractures?
Yes, it is. In fact, fractures are repaired all the time with emeralds, routinely enhanced. Mineral oil is added to conceal the fractures; this is not considered to be a fraud according to the FTC, or Federal Trade Commission. In rubies, leaded glass flux is added to clarity enhance the gems by filling fractures. Laser drills are used to remove inclusions in Diamonds including cleaning large fractures, then a strong flux is added. This is heated and baked at high temperatures to basically repair the fracture. All treatments as such, must be disclosed to consumers by law.
What is the cause of abnormal gemstones, such as blue diamonds and pink sapphires?
The different colors in gemstone, is caused by coloring agents and impurities available at the time of a particular crystal formation including iron, manganese and cobalt. For example, nitrogen is responsible for yellowish diamonds, and boron leads to blue diamonds. Although most sapphires are blue, pink sapphires are due to a high chromium quantity. The color in pink diamonds is still subject to scientific investigation.
Can gemstones influence the environment in which they are formed?
Studies are being conducted on this topic. Some gemstones can influence the environment in which they are formed. For example, geodes are crystals formed within volcanic or sedimentary rock. An organic gemstone, amber,, is hardened tree sap. When sticky, it can trap insects and other tiny animals, thus preserving them in a kind of time capsule. Gemstones can also dramatically affect the environment during the mining process, which may be destructive.
What are some of the easiest and hardest gemstones to work with?
Some easier gemstones to work with can be cut in a cabochon manner, which is described as having a convex top and a flat bottom. These stones are often opaque and highly included. It is a quick job to prepare stones such as opals, agate, and tigers eye in this way. However, more transparent gemstones, such as corundum – ruby and sapphire – are often faceted. This is more complicated, as facets must meet precisely at one point. The risk of damaging a valuable gemstone requires only experts to work at this job.
How long does it take to distinguish between very similar types of gemstones?
It depends, some gemstones take longer to identify than others. A refractive index test only takes a few minutes, and is usually all that is required. However, in the case of aquamarine and Blue Topaz, you can use a special filter, and you get an answer in seconds. Blue topaz is red and aquamarine is green under this filter.
Do you have any favorite stones to work with, or are they all equally interesting?
All gemstones are interesting to me. However, diamonds are always the best. They have a structured market and always excellent to get an opportunity to work with them. Still, other gemologists and jewelers have their own, different preferences.
