How to identify a natural Burma ruby from a heat-treated one.

## The pigeon-blood test A true Mogok ruby glows like a candle through bone china. Look for fine silk needles, mild fluorescence under shortwave UV, and a slightly bluish secondary tone. Heat treatment removes the silk and gives a pure, almost neon hue — beautiful, but no longer untouched. For investment-grade pieces always insist on a Gübelin, SSEF, or AGL certificate from the country of origin.