Keep Informed (8.05)
Synthetic diamonds are a fact of the trade and at this point in time they must be addressed in an informed manner. Even though they are not as yet, commonplace, that will inevitably change with time. Current technology is very close to a major breakthrough in the production of white synthetic diamonds at a fraction of the cost of its natural counterparts. But with this new product, new technology for identification will undoubtedly emerge. Our newsletter will keep you updated on the latest detection developments.
Nobel prize winner Henri Moissan discovered natural silicon carbide inside a Canyon Diablo meteorite. The substance was then named moissanite. After much research and development, synthetic moissanite (synthetic silicon carbide) was able to be grown into large crystals for jewelry applications. Before that, silicon carbide was used for decades as an industrial abrasive (and still is).
Using the Relative Mohs Hardness Scale, it is rated 9¼. This would make it harder than corundum, but much softer than diamond. Remember the hardness range between 9 and 10 far exceeds the difference in hardness between 1 and 9 on the scale. Hence moissanite is still a very hard substance, producing much sharper facet edges than for softer stones (and will remain so).
Diamond’s specific gravity is 3.52, whereas moissanite’s is 3.22. This indicates that moissanite is 91% of diamond’s weight, given the exact same proportions (or volume). So an easy way to identify or confirm the authenticity of moissanite would be to use the diamond weight estimation formula (discussed in greater detail in section 11).
For example, suppose the stone in question measures: 6.41 - 6.43 x 3.80 mm
Average diameter: 6.42 Depth: 3.80
Formula would read:
6.42 x 6.42 x 3.80 x .0061=0.96 carat for a diamond.
Your carat scale shows a weight of 0.87 carat which would indicate a moissanite since it is 91% of the estimated diamond weight. At the very least you would be sure it is not diamond.
Clarity in moissanite varies from many needle-like inclusions arranged in directions parallel to the pavilion surfaces, to high clarity (clean).
The color of moissanite also varies, but it will usually be obviously tinted in the subtle yellows, browns, greens, greys or mixtures thereof. Undoubtedly C3, the manufacturer of moissanite, will try to further improve this color for obvious reasons.
Polishing lines generally all run in the same direction on moissanite, since grain direction does not have to be taken into account in the polishing process. Remember that a diamond’s polishing lines will always run in multiple directions.
Rounded facet edges are another indicator of moissanite, but with better manufacturing methods and more skillful cutters, this may not be sufficient alone to confirm your identification.