Ruby

Ruby's red comes from chromium replacing aluminium in the corundum structure; more chromium generally means stronger red and stronger red fluorescence, which can make fine rubies appear to glow. Hues range from purplish red through pure red to slightly orangey red, with the vivid pure reds most prized. Sri Lankan rubies tend towards pinkish and purplish reds rather than the deepest crimson associated with classic Myanmar stones, and lighter Sri Lankan material grades into pink sapphire. The boundary between ruby and pink sapphire is not universally fixed, so laboratory descriptions matter for borderline stones. Fluorescence, tone and saturation together give each ruby its individual character, best judged under several light sources.

Colour dominates ruby valuation: vivid saturation, medium to medium-dark tone and a pure red hue are the ideal. Clarity expectations are more relaxed than for sapphire, some inclusions are normal and fine silk can even improve colour distribution, but fractures that threaten durability or transparency reduce value sharply. Cut affects brilliance and colour return, and well-proportioned rubies are scarce because cutters maximise weight from costly rough. Treatment status is critical: unheated rubies of fine colour are exceptionally rare and command large premiums, while lead-glass filled rubies sit at the opposite end of the market. For any significant ruby, a report from a recognised gemmological laboratory is indispensable.

Most rubies on the market are heated to improve colour and clarity, an accepted practice when disclosed. Two further treatments demand particular attention. Lead-glass fracture filling transforms heavily fractured, low-grade corundum into saleable-looking stones; such composites are fragile, damaged by household chemicals and jeweller's tools, and must be sold clearly identified as filled or composite rubies at appropriately low prices. Lattice diffusion also occurs. Under international trade standards, notably CIBJO's Gemstone Book, one of the Blue Book standards published by the World Jewellery Confederation, treatments should be disclosed at every stage of sale, and consumer-protection law in many jurisdictions separately requires material facts such as treatment to be disclosed. Because filled rubies can look convincing, and the price difference between treated and untreated stones is enormous, laboratory testing is the only safe basis for buying any ruby of consequence.

Sri Lanka recovers ruby from the same alluvial gravels that yield its sapphires, in districts such as Ratnapura and Elahera and southwards towards Embilipitiya. The island's red corundum has entered world trade since antiquity, and historical accounts of Ceylon's gems frequently mention red stones, though some early references confused ruby with spinel. Today the most celebrated ruby origins include Myanmar and Mozambique, with Sri Lankan stones respected for bright, lively pinkish reds. Laboratories can often support origin opinions from inclusions and trace-element chemistry. For buyers, origin influences price meaningfully in ruby, but colour, clarity and treatment status remain the first considerations.

Ruby shares corundum's outstanding durability, hardness 9, no cleavage, and untreated or simply heated rubies handle daily wear and ultrasonic cleaning well. Lead-glass filled rubies are the important exception: the filler is attacked by common substances including household cleaners and can be damaged by heat from a jeweller's torch, so such stones need gentle hand washing only and their treated status must be told to any jeweller working on the piece. When in doubt about treatment, clean gently with warm soapy water and a soft brush. Store rubies separately from softer gems, protect edges from knocks, and have settings inspected periodically.