However, there is no general agreement on how to draw the line between rubies and sapphires.ĭepending on the chromium and iron content, rubies have a color range that includes pinkish, purplish, orangey, and brownish reds. Stones lighter than this are called pink sapphire. Most gemological authorities expect a medium to medium dark-red color tone in a ruby. All other color varieties of gem-quality corundum are referred to as sapphire. Synthetic rubies: see 'Synthetics' below. Zircon crystals with halo of dark fractures, fingerprints, hexagonal growth lines, color zoning. Natural rubies: silk, rutile needles, usually crossing at a 60 degree angle. Also, igneous rocks such as granite and nepheline syenite. Metamorphosed crystalline limestones and dolomites, as well as other metamorphic rock types such as gneiss and schist. Even mauve and purple sapphires have a trace of Cr and show these lines). (The reversible fluorescent doublet is a sensitive test for the presence of chromium in a corundum. Broad absorption of yellow, green, and violet. Heat treated (common), fracture-filled (occasional), lattice diffusion.įracture/Cavity Filling, Heat Treatment, Infusion/Impregnation, Lattice DiffusionĪ distinctive spectrum a strong red doublet at 6942/6928 is notable, and this may reverse and become fluorescent. (May have blue over-tint)įluorescent, UV-Long, UV-Short, X-ray Colors

Flux Grown: strong in LW, orange/red, moderate to strong in SW, orange/red. Flame Fusion: very strong in LW, orange/red, moderate to strong in SW, orange/red. Sri Lankan ruby fluoresces strong orange-red in LW, pink (moderate) in SW. Thai ruby fluoresces weak red in LW, weak or none in SW. Red fluorescence is, however, not diagnostic of country of origin or natural origin. Myanmar stones fluoresce intensely, red, in SW, LW, and X-rays. For more information on ruby quality factors, consult our buying guide and appraisal guide.įlux-Grown Ruby, Geneva Ruby, Star Ruby, Verneuil RubyĪll varieties of red, from pinkish, purplish, orangey, brownish, to dark red. Origin and color greatly affect the value of a ruby. Photo courtesy of and Burchard Galleries. 18k yellow gold, 1-ct ruby, and 0.15 ctw diamonds. While these cuts retain much of the mass of the rough stones, the resulting gems have irregular shapes and don’t look very lively. This is a beautiful antique ring, but the ruby and diamonds have received native cuts.

Origin 8 cutler 7 price