Which laboratory method creates the best synthetic corundum for faceting?
It all depends on why you want to facet the best synthetic corundum in the first place.
There are many ways of making synthetic corundum, both ruby and sapphire. Flame fusion is the least expensive method of synthesizing any stone. Hydrothermal synthesis is the most expensive. This involves growing a crystal from a solution under great heat and pressure. Not only is the equipment for this process expensive, it also takes weeks or months to grow crystals. However, hydrothermal is the synthetic technique that mimics most closely natural gemstone formation. There are other methods of making corundum, too. Their manufacturing costs are just slightly higher than flame fusion.
Distinguishing natural from synthetic corundum gems takes magnification and careful analysis. With this in mind, flame fusion rubies and sapphires are a fine choice for most faceting. If you simply want to cut a beautiful stone, flame fusion is your best option. However, if you want more value from your finished stone, use a hydrothermal. You may be able to sell your faceted hydrothermal ruby or sapphire for a higher price. The best synthetic corundum, bottom line, is what will give you the best return for your effort.
Donald Clark, CSM IMG