If you’re buying a $1,000 one-carat emerald, you should find out if coloured fillers have been used on the emerald and if the enhancement has had a major impact on its clarity. You wouldn’t want to pay $1,000 for an emerald that in its unenhanced state is worth, say, $400. To avoid this, select an emerald with good transparency and as few surface cracks as possible. Deal with ethical sellers who know how to judge emerald quality and examine the stone under magnification.
It could also be helpful to have the stone examined by a Gemmologist. As the price of the emerald goes up, it becomes more and more worthwhile to get a full lab report from a lab.
Most of the major labs now indicate the extent of fracture filling according to the following scale:
Some Laboratories indicates the degree of enhancement and rarity on their reports according to the following scale:
If you were to buy a $20,000 emerald, it would be in well worth your while to find out what type of filling was present as well as the degree of clarity enhancement. You probably would not be buying the $20,000 emerald only for its beauty and romance. Most likely you would view your purchase partially as an Investment or you would be buying the stone for resale. In either case, you should consider its marketability, and you should have information about the emerald that would be helpful to potential buyers.
Many dealers would refuse to buy a $20,000 emerald treated with hardened or permanent fillers, They don’t want to spend that much money on a stone with a solidified filling that’s difficult or impossible to take out. Neither do they want a filler that will turn cloudy in a few months.
Cedarwood oil and Canada balsam are accepted fillers. Dealers will buy emeralds with either of these fillers from you if they’re worth the price asked and if the effect of the enhancement is minimal.
Rarity plays a major role in the pricing of gems. Untreated eye-clean emeralds are rare, as are those with a minimal amount of filler. Consequently, emeralds command premium prices. On the other hand, emeralds with a significant amount of filler are discounted.