AN UNMOUNTED FANCY DEEP YELLOWISH GREEN "CHAMELEON" DIAMOND
Weighing 6.90 carats
With certificate 0208024 dated 19 August 2002 from the Gübelin Gemmological Laboratory stating that the diamond is fancy deep yellowish green, natural colour and changes to fancy intense yellow temporarily when heated, or when left in darkness for a period of time and is known in the trade as "CHAMELEON". Also accompanied by an appendix stating that diamonds are classified into two fundamental groups based on the relative presence or absence of nitrogen incorporated into the crystal structure, as determined by the infrared spectrum. Type I diamonds contain appreciable concentrations of nitrogen, whereas type II diamonds are chemically very pure and do not reveal infrared absorption characteristics related to nitrogen.
A further seperation of these two groups includes type Ia (nitrogen atoms present in pairs or groups), type Ib (isolated nitrogen atoms), type IIa (no measurable traces of nitrogen) and type IIb (traces of boron).
Based on its infrared spectrum, the 6.90 ct diamond is classified as type Ia