Curious whether a particular gemstone is natural or lab-grown?
All lab grown gemstones of any color have essentially the same basic gemological properties as do the natural gemstone. In fact, one of the greatest gemological challenges still facing jewelers today is to determine whether a gemstone is natural or lab grown.
By definition, lab grown gemstones have the same optical and physical properties as natural. Therefore, instrument test generally relied on by gemologist and jewelers, such as refractive index or specific gravity testing, methods that would help separate rubies, sapphires or emeralds or imitations such as doublets triplets or glass/plastic, would be essentially useless in separating natural gemstones from lab grown.
Direct observation of the gemstone under magnification is the best way to separate lab grown from natural. Lab grown methods commonly leave behind telltale evidence in the form of inclusions not found in natural gemstones.
Whether or not those lab grown gemstones are recognized as such is a direct result of gemological training. Only a trained Gemologist with GIA or AGS training is qualified to make that determination.