As we embrace July, let’s celebrate the captivating corundum ruby! Renowned for its rich red hue, this gem symbolises passion, vitality and protection. The name “ruby” comes from the Latin word “ruber,” meaning red. The July birthstone is part of the corundum family, which also includes the stunning sapphire.
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What Makes the Gem Red?
Corundum is crystalline aluminium oxide. When traces of chromium replace some of the aluminium in the crystal lattice, the result is red, and only red corundum may be called ruby – every other colour, from blue to pink to yellow, is a sapphire. The dividing line between pink sapphire and the July gem is a matter of saturation and is one of the most debated boundaries in gemmology.
With a hardness of 9 on the Mohs scale, it is second only to diamond, making it an excellent choice for rings and bracelets that are worn every day. Chromium also causes many stones to fluoresce red under ultraviolet light, which gives the finest examples their famous inner glow.
Where Rubies Come From
Rubies are found worldwide, from the breathtaking landscapes of South and Southeast Asia to the renowned deposits in Africa and North America. The Mogok Valley in Myanmar (Burma) has produced the most celebrated stones for centuries, and “Burmese” remains the benchmark against which others are judged.
Since the discovery of the Montepuez deposit in 2009, Mozambique has become the world’s most important source by volume, producing stones of excellent colour and clarity. Thailand, Sri Lanka, Vietnam, Madagascar, Tanzania and Greenland also contribute to the market, each with its own subtle characteristics that help laboratories determine origin.
Pigeon Blood: The Colour That Defines Value
Their value often hinges on colour, with the highly sought-after “pigeon blood” red leading the pack. The term describes a vivid, pure red with a hint of blue and strong red fluorescence, traditionally associated with the finest Burmese material. Stones that are too dark, too orange or too purplish fall away in price quickly.
Clarity is judged more leniently than in diamond, as some fine silk (needle-like rutile inclusions) is expected and can even enhance the colour by scattering light. Fine, untreated stones over three carats are extremely rare, and prices per carat climb steeply with size.
Treatments and Imitations to Be Aware Of
Most rubies on the market have been heated to improve colour and clarity, a stable and accepted treatment that must be disclosed. Our article on identifying heat treatment in corundum explains the tell-tale signs we look for under the microscope.
- Lead glass filling: heavily fractured material is filled with high-lead-content glass. These stones are fragile and worth a fraction of an untreated gem. Read our guide to lead glass filled ruby.
- Synthetics: flame-fusion and flux-grown synthetics have been produced since the 1900s. Curved growth lines and gas bubbles often give them away.
- Imitations: red spinel, garnet and glass have all been passed off as the July gem; the Black Prince’s Ruby in the Imperial State Crown is in fact a spinel.
Ruby Symbolism and History
Fun fact: throughout history, rubies have been believed to inspire courage and self-confidence! In ancient Sanskrit the stone was called ratnaraj, “king of precious stones,” and Burmese warriors are said to have inserted them under their skin to make themselves invincible in battle. Today it is the gift for a 40th wedding anniversary as well as the July birthstone.
For a reliable overview of the gem’s properties and history, the Gemological Institute of America (GIA) maintains an excellent encyclopedia entry. You can also explore July’s lesser-known alternative, onyx, and the rest of the year on our birthstones page.
Buying a Ruby with Confidence
Because colour, origin and treatment all have such a dramatic effect on price, an independent laboratory report is essential for any significant purchase. At E.D.R – European Diamond & Gemstone Reports in London we identify natural versus synthetic material, detect heating and glass filling, and issue a Loose Gemstones Report you can rely on.
Let this glorious July birthstone guide your journey this month at E.D.R, where we celebrate the scientific wonders of gems. Get in touch to have your stone examined, and stay tuned for more on the enchanting world of birthstones!
