This term is sometimes used to describe a treatmentcommon to jade and some other gem materials inwhich a substance such as wax is rubbed on the surfaceof the stone to improve its appearance. The waxis only present on the surface and in depressionssuch as grooves in carvings, so it is not considered animpregnation. Although such substances are sometimesapplied to pearls (Petersen, 2000), lusterenhancement of pearls typically has a somewhat differentmeaning.
In the cultured pearl industry, the name Maeshoriis associated with this kind of treatment (Akamatsu,2007; Shor, 2007). Developed in the 2000s to improvethe prepolishing process, it involves the use of solventsto “clean” nacreous pearls and hence produce a morelustrous surface. Various other forms of this treatmentalso exist (Lingyun et al., 2007). Polishing continues tobe used on all types of nacreous and non-nacreouspearls to improve their salability. It takes place at allsteps of the supply chain (Pousse, 2001), starting withthe farmers, who often tumble their cultured pearlswith walnut chips (N. Paspaley, pers. comm., 2008)and/or other materials and then polish them.
The first decade of the 2000s brought many new,unanticipated enhancements. Some of these—suchas HPHT treatment and beryllium diffusion ofcorundum—usually cannot be identified by gemologistswith standard equipment. In most cases, stonesthat might be treated by these methods must be sentto a well-equipped gemological laboratory to get aconclusive identification. Still, today’s gemologistcan benefit by developing their ability to recognizewhen a stone shows evidence it has not been treated(particularly for rubies and sapphires) and also recognizingwhen they cannot tell and the stone must besent for further testing.
It is interesting that in their retrospective of the1990s article, McClure and Smith (2000) predictedthat new filling processes would bring clarityenhancement to ruby, sapphire, and alexandrite.Three years later, at least part of this predictioncame true with the development of a lead-glass fillerfor ruby. There is every reason to believe that thistreatment, or a similar one, will soon extend to otherrelatively high RI materials.
Already in 2010 we have seen several new developments,including lead-glass filling of star rubies(Pardieu et al., 2010a) and a combination treatmentof rubies from Mozambique that includes partialhealing of fractures and partial filling with a glassthat does not contain lead (Pardieu et al., 2010b).
With these developments, disclosure has becomea significant topic at every trade show and gemologicalconference. As the trade discovered with emeraldfillers (and the impact of nondisclosure on emeraldsales) in the ‘90s, they neglect this subject at theirperil. Consensus is critical. Discovering a treatmentexists and developing identification criteria are animportant start, but the trade and gemological communitymust work together to address the issues ofwhat to call a treated material, how to disclose it,and how to make sure it gets disclosed. Importantsteps in this direction have been made, but more areneeded.
McClure and Smith (2000) also predicted—correctly—that technology would advance at an evenfaster rate during the next decade. This willundoubtedly be the case from now on, making theunforeseen the norm in the gemological world as itis in the world at large.