Ruby Crystals in Matrix, Mysore, India

Contributed by: Chris Clemens
minID: PX5-9M6
Date: Apr 16th, 2026
Locality: Mysore District, Karnataka, India (See on Mindat)
Size: 13 x 6.4 x 18.3 cm
Weight: 2010 g

Description:
Raspberry red-colored hexagonal crystals of corundum (var. ruby) in a granite-like matrix was collected from an unidentified mine in Mysore, Karnataka, India. This corundum specimen from Mysore, India is especially rich in brightly fluorescent ruby crystals. The luscious, velvety red response is activated by trivalent chromium, which substitutes for some of the aluminum in the crystal lattice. The matrix shows pale blue-white fluorescence, which contrasts aesthetically against the bright red response of the ruby crystals. The largest crystal in this specimen measures 19.2 mm in length.

Originally posted by Chris Clemens on Nature's Rainbows in 2022.

Afterglow after exposure to longwave UV light.

Normal light.

Fluorescence under longwave UV light. Closeup. The crystal measures 19.2 mm in length.

Normal light. Closeup. Note the light-colored reaction zone surrounding the crystal.

Summary of luminescence responses:

Corundum var. Ruby (Mindat) (RRUFF)

• Fluorescence under Longwave (365nm LED) UV light: Red