In early August 2005, gem and mineral dealer Dudley Blauwet (Dudley Blauwet Gems, Louisville, Colorado) informed these contributors about a new find of pinkish orange to purple sapphires from India. According to his supplier, the material comes from the Kurur area of Tamil Nadu State, and much of it has been collected by farmers from near-surface secondary deposits. Mining has been hindered by the lack of available water to wash the soil, but rough parcels weighing 200–300 grams occasionally have been obtained by a few local dealers.

The rough is recovered as broken fragments, some of which are rather large (i.e., up to 12–20+ grams). However, most of the material is extensively fractured, so typically the cut stones weigh up to 1–3 ct. Nevertheless, the largest faceted stone that Mr. Blauwet was informed about weighed approximately 30 ct.

Most of the sapphire is found in shades of lavender and pink, and is heated to 1,100°C in Sri Lanka. The resulting coloration typically ranges from orange to amethyst-like purple colors, commonly with strong color zoning (see figure). The blue component has proved difficult to remove from the “silky” lavender rough, but heating to higher temperatures is avoided due to the risk of causing more fractures in the material.

Mr. Blauwet donated one unheated and two heated sapphires to GIA, and also loaned 14 heated sapphires for examination (0.36–3.87 ct). Gemological examination of six representative stones (0.36–1.70 ct) revealed the following properties: color—purplish pink to orangy pink, with one stone being a brownish pinkish purple and another being distinctly bicolored reddish purple and reddish orange face up; pleochroism—red-to-orange or red-to-purple; R.I.—1.760–1.769, with a birefringence of 0.008–0.009; and S.G.—4.0. When viewed with a gemological microscope, the samples displayed uneven coloration in zones or bands, as well as groups of short, fine rutile needles, fine-grained clouds, lamellar clouds, clouds of tiny reflective platelets sometimes interspersed with rutile needles, and “fingerprint” inclusions. They exhibited weak-to-moderate red fluorescence to long-wave UV radiation, and weak red or no fluorescence to short-wave UV. Typical features seen with a desk-model spectroscope included a weak absorption band at 460 nm, a 475/480 nm doublet, and a band at 670 nm.

Although the colors of some of these samples resemble those seen in sapphires treated by Be diffusion, the samples showed no evidence of the high temperatures used in that process. According to Mr. Blauwet, much of this Indian sapphire is being sold on the market as heated Sri Lankan or Madagascar material.

Shane F. McClure
GIA Laboratory, Carlsbad

James E. Shigley
GIA Research, Carlsbad

Brendan M. Laurs