Here we'll just briefly discuss some of the commonly misunderstood concepts observed in the local trade. Now, certain people may already be aware of these, but it seems that every now and then some people express confusion regarding what many terms mean, and what they don't mean. This short article should give you a bit of insight (and trivia) about gemstones and jewelry.
1. '
Emerald Cut' refers to a specific cutting style and shape, not necessarily or specifically to the emerald gemstone itself. Most diamond collectors may be familiar with the popular term 'emerald cut', but some people are not aware that this term refers to how a gemstone (diamond or any other) is fashioned and polished into a rectangular shape with step-cut (four sided) facets on its body. Emeralds themselves, are very often cut in this rectangular style, because of the way their crystals grow, and the intention of gem cutters to save the most weight. Today, many other gemstones, such as aquamarine, diamond, amethyst and quartz are frequently fashioned as 'emerald cuts'. This specific cutting style is well suited for stones of high clarity, or stones that tend to form elongated or columnar in nature.
2. Rubellite is not ruby. We've come across a few parties that previously believed rubellite to be a form or type of ruby. This is simply not true. Rubellite is a trade named color variety for red to pinkish red tourmaline. Both tourmaline and ruby maintain very differnet gemological properties, and prices. Ruby is traditionally much more expensive than rubellite tourmaline, given a situation where color intensity and clarity levels are generally equal.
3. The term 'synthetic' is different from the term 'imitation' or 'simulant'. A synthetic gem refers to a man-made counterpart of that gem, with the same essential crystal structure and chemistry. A synthetic diamond, is still made of carbon, crystallized in the cubic crystal system for example. This is in stark contrast to an imitation gem (also called a simulant gem). An imitation gem merely looks like the gem it is trying to copy. Moissanite for example, is an imitation of diamond, as it is made of silicon carbide instead of pure carbon. It also grows in a different crystal system.
4. Cultured Pearls, not wild pearls, comprise a majority of all middle to high-end pearl jewelry collections in the country. Some people are not aware that over 99% of all pearls used in the jewelry industry today (especially the mid-to-high ranges) are actually cultured pearls. Cultured south sea pearls for example, are among the most expensive pearl items you can procure, with some necklaces costing hundreds of thousands of dollars. For pearls there are three categories you have to be familiar with. Imitation pearls, cultured pearls and wild-caught pearls. Imitation pearls are simply simulant items usually made of plastic or glass coated with iridescent substances. Cultured pearls and wild-caught pearls both come from actual live animals (mollusks, oysters etc), but a cultured pearl means that man has assisted the developmental stage by putting either a piece of mantle tissue or a shell-bead nucleus inside the mollusk in order for it to coat with nacre over long periods of time- to eventually form a pearl. The nacre layers are still organically produced by the same animal. Wild-caught pearls statistically speaking, are rare coincidences in nature today, and almost never come in large enough symmetrical shapes (round, oval etc.). The vast majority of fine pearl jewelry makes use of cultured pearls.
(This statement does not apply for giant clam pearls, which we do not currently test at the laboratory).
5. Diamonds are not indestructible. We would not suggest that people perform any possibly-destructive test to find out if their stone is actually a diamond. Stories of sandpaper-scratching or hardness testing using rocks or other materials seem to be very prevalent among Filipinos. While diamond is the hardest mineral to 'scratch', it does maintain multiple planes of atomic weakness (cleavage). When struck in specific directions, a diamond can chip, fracture or even split in two. Thin areas of a diamond, like its girdle or culet, are also very prone to breakage. This can still happen even if it impacts with something with a generally lower hardness, if done in certain ways. Additionally, diamonds can also burn if subjected to high enough fire temperatures and sufficient levels of oxygen (because they're still carbon).
6. Proper heat treatment in rubies and sapphires is okay and an accepted part of the trade. There are those out there who detest the thought of their rubies being treated, but the vast majority (over 95%) of rubies and sapphires today are actually subjected to some form of heat treatment. It's a normal practice in the industry, and can bring out a stone's potential when done in the correct conditions using appropriate methods. While premium prices do exist for unheated stones, it's just as likely that an originally duller stone's value can eventually be heightened by subjecting it to heat treatment and increasing the overall color quality.
7. Glass-filled rubies are not nearly as expensive as natural or heated-only rubies. These items can be filled with glass in up to 50% of their composition. If someone tells you that their value is basically the same as rubies that aren't filled, you should probably do a bit of research first. Most likely you'll find that glass-filled rubies were originally very opaque-looking low-quality stones. Their durability post-treatment is also not that stable, according to many of our visitors and our own observations.
8. DIY Handheld Diamond Thermal Testers cannot differentiate between natural diamonds and lab-grown / man-made diamonds. These instruments make use of a technology that measures thermal conductivity, a property that is essentially the same for both natural and synthetic diamonds. Other testers like duo or multi testers that also check for moissanite, make use of electrical conductivity. These also cannot separate CVD or HPHT lab grown diamonds from natural diamonds. Advanced spectrometric testing is more suitable for this differentiation, which we make use of here at Gemcamp Laboratories.
