Some experts estimate that what fraction of colored gems is now treated?

• A. 1/2
• B. 3/4
• C. 1/4
• D. 1

Answer: (B)

The idea being tested is how common treatment is in colored gemstones today. Treatments are so widespread in the trade that many experts describe the market as being dominated by enhanced stones. This high prevalence comes from the fact that enhancement makes colors more vivid, improves clarity, or increases durability, which buyers expect and sellers provide. Because of this, about three-quarters of colored gems are estimated to be treated. This figure covers a range of techniques—from heating to deepen or alter color in rubies and sapphires, to diffusion or irradiation for stronger hues, to fracture filling and dyeing to improve emeralds and other stones. While not every colored gem is treated and some remain entirely natural, the overall level of treatment is high enough that 75 percent is a reasonable, widely cited approximation.