Naturally-Coloured and Treated Yellow and Orange-Brown Sapphires

Section: The Gemstones Of Elaherasupporting

confidence: 79%

The Elahera Gem Field in Central Sri Lanka

Gunawardene¹,

Rupasinghe²

1986

“…Broad chromium pealzs in natural pinlz sapphires and rubies occur at roughly 410 n m and 550 nm, whereas the pealzs in synthetic Ti-sapphires are seen at approximately 390, 485, and 560 nin. The natural orangy pinlz sapphires that we have seen, and that have been reported in the literature (Schmetzer et al, 1983;Fritsch and Rossman, 1988), contain chromium and iron (sometimes determined to be Fe3+) or chromium and magnesium (Mg2+). Therefore, they show chromium spectra in addition to other features.…”

Section: Discussionmentioning

confidence: 62%

"Ti-Sapphire": Czochralski-Pulled Synthetic Pink Sapphire from Union Carbide

Johnson¹,

Mercer²,

Fritsch³

et al. 1995

One of the most interesting of the commercially available CzochralskiCzochralski-pulled synthetic sapphire was originally grown for technological applications, which require pure crystals with good clarity and even color distribution. Consequently, materials originally intended for such applications can be excellent candidates for use as gems. Czochralskipulled synthetic rubies have been known for a number of years (see, for instance, Nassau and Crowningshield, 1969, and references cited by

“…A good general review is provided by Rossman (1987, 1988);Häger (2001) orangy yellow (Kvapil et al, 1973;Schmetzer, 1981;Schmetzer et al, 1983;Boiko et al, 1987;Emmett and Douthit, 1993;Häger, 1993 …”

Section: Color In Corundummentioning

confidence: 99%

Beryllium Diffusion of Ruby and Sapphire

Emmett¹,

Scarratt²,

McClure³

et al. 2003

Over the past two years, the heat treatment of corundum involving lattice diffusion of beryllium (Be) at temperatures over 1800°C has become a major issue in the gem trade. Although initially only orange to orangy pink ("padparadscha"-like) sapphires were seen, it is now known that a full range of corundum colors, including yellow and blue as well as ruby, have been produced or altered by this treatment. An extension of the current understanding of the causes of color in corundum is presented to help explain the color modifications induced by Be diffusion. Empirical support is provided by Bediffusion experiments conducted on corundum from various geographic sources. Examination of hundreds of rough and faceted Be-diffused sapphires revealed that standard gemological testing will identify many of these treated corundums, although in some instances costly chemical analysis by mass spectrometry is required. Potential new methods are being investigated to provide additional identification aids, as major laboratories develop special nomenclature for describing this treatment.