GFCO GEM LAB always checks treatments for rubies, sapphires, emeralds and jade. Upon request and if possible, the laboratory checks treatments for spinels and opals.
The equipment used for testing features on the left page of the report and unless indicated otherwise is standard equipment only. Any comment of importance and limitation in the depth of testing features on the left page of the report which is an integral part of the report. The laboratory may upon request and at extra costs proceed to testing with advanced equipment, such information is to feature on the left page of the report.
STANDARD HEAT : also known as "old heat" - a simple heat treatment. Such treatment may leave residues of the substance with which the gemstones was heated in healed fissures and small fissures and possibly as filling in cracks, internal cavities and surface cavities (→ see "presence and quantification of residues/filling for rubies and sapphires" thereafter).
FILLING HEAT : also known as "new heat" - a heat treatment at low temperature with purpose of clarity enhancement by filling fissures, cracks and cavities with a glass-like substance (commonly lead glass). In heavily fractured and crackes gemstones, this treatment may cause some problems with the durability of the gemstones and risks of the gems to break when mounted into settings - such stones are commonly called "glass-filled". This treatment should not present the same issues for gemstones with only a few fissures.
LIGHT ELEMENT HEAT - also known as diffusion : a heat treatment with adding of one or more chemical elements (usually beryllium) in order to enhance color where the element penetrates deeply inside the gem.
HEAT * : the gem has been heated; the laboratory has not determined if light elements have been added to the heat treatment.
LATTICE DIFFUSION - also known as "surface diffusion" : a heat treatment with adding of one or more chemical elements (usually titanium) in order to enhance color where the element penetrates the gem only near its surface. HEAT * : the gem has been heated; the laboratory has not determined if light elements have been added to the heat treatment.
CLARITY ENHANCEMENT : The gem has been clarity enhanced by either natural oil or a chemical oil or a resin. Identification of the filling substance with certainty requires further testing of the item with advanced technologies.
OIL : The gem has been clarity enhanced by oil.
RESIN : The gem has been clarity enhanced by a type of resin.
COLOUR ENHANCEMENT : The gem has been coloured enhanced by a method such as impregantion with a colouring agent, a colouring agent in the filling, surface coating or surface painting. An extra-comment will state the method.
PRESENCE AND QUANTIFICATION OF RESIDUES/FILLING FOR RUBIES & SAPPHIRES: applies only for STANDARD HEAT and FILLING HEAT (not specified for all others treatments). Shall there be no presence of residues, no comment will feature. Quantification of residues is expressed by INSIGNIFICANT, MINOR, MODERATE, SIGNIFICANT and VERY SIGNIFICANT followed by number (1) or (2) where:
(1) = residues/filling limited to healed fissures and small fissures;
(2) = residues/filling in cracks and/or cavities and/or surface cavities and possibly healed fissures and small fissures.
PRESENCE AND QUANTIFICATION OF CLARITY ENHANCEMENT/OIL/RESIN FOR EMERALDS : Shall there be no clarity enhancement, NO TREATMENT will feature. Otherwise, the clarity enhancement degree is expressed by INSIGNIFICANT, MINOR, MODERATE and SIGNIFICANT followed by (PCF) if presence of internal and/or surface cavities filling.
RESIDUES/FILLING FOR RUBIES & SAPPHIRES:
Depending on the gemstone origin and landscape of inclusions, some treatment may be identifiable with certainty only by testing with advanced equipment. It can be the case of standard heat treatment, low heat treatment and lead glass in extremely light proportion. Similarly, separation of standard heat from heat with ligh element (beryllium) may require chemical testing in several situations. Obviously, such testing is costly due to the nature of the equipment. However, there also exist situations in which advanced equipment is of no use and where the analysis relies only on the gemologist experience with microscope (e.g. basaltic stone.).