Ruby: meaning, properties and lore

The mineral

Ruby is a gemstone made of transparent red corundum, a mineral form of aluminium oxide with the chemical composition Al₂O₃. Corundum is relatively hard and tough, and it is, next to diamond, the hardest of all stones.^1234567

Corundum, which ruby is a variety of, crystallizes in the hexagonal system and has a Mohs hardness of 9. Ruby's hardness is second only to diamond. The primitive crystal form of all corundum kinds, including ruby, is a slightly acute rhomboid. The most common shape of ruby crystals is a flat tabular hexagonal form.¹³²⁸⁹⁵

The red colour of ruby comes from chromium. The more chromium present, the stronger the red. In its purest form corundum is colourless, and trace elements in its crystal structure cause its variations in colour.¹³⁴²

Ruby has a specific gravity of 4.00 (plus or minus 0.05) and a refractive index of 1.762 to 1.770, with birefringence of 0.008 to 0.010. It is pleochroic, typically red to purplish red in one crystal direction and orangy red in the other. Ruby has high refractivity and weak dispersion, so when cut and polished it is a brilliant stone but lacks fire.^3106879111

Ruby changes under heat and light. On exposure to high temperature it becomes green but regains its original colour upon cooling. Under radiant discharge it phosphoresces with a vivid red glow. Fine ruby glows intense red in sunlight because of red fluorescence, which chromium can cause and which intensifies the red. Higher iron content can mask that red fluorescence.¹³⁴

Ruby is a mineral of very limited distribution, and its best known localities are in north-central Myanmar, northeast of Mandalay. The Mogok valley there is a legendary source of rubies. Rubies have also been found at several localities in Thailand, in gravels with sapphires and spinels, generally of dark colour. Other producers include Luc Yen in northern Vietnam and Mozambique, with prolific mines at Montepuez.¹³²

The most renowned rubies, such as those from Myanmar, the Himalayas and northern Vietnam, typically form in marble, a metamorphic rock, and they lack iron because marble has low iron content. Marble-hosted rubies typically fluoresce red under ultraviolet light. Rubies can also be found in basalt, where higher iron content can make them darker and less intense in colour. Rubies from Sri Lanka's gem gravels are not usually of as good a colour as Myanmar stones.⁴¹²¹

History and lore

The word ruby comes from the Latin ruber, meaning red, according to the Gemological Institute of America. In Sanskrit ruby is called ratnaraj, meaning the king of gems, and in ancient India it was called the king of precious stones. Historically the word ruby referred to shades of red, which technically included pink, and the term pigeon's blood described the red to slightly purplish or pinkish red colour of rubies with a soft, glowing red fluorescence.^13123211

The Roman scholar Pliny included rubies in his Natural History in the first century AD, describing their hardness and density. Romé de Lisle, the first mineralogist to classify gems on crystal form, placed oriental ruby at the head of the class of stones harder than all others except the diamond. Count de Bournon described corundum and its varieties, including oriental ruby, in a paper read before the Royal Society on March 25, 1802.¹³⁶⁸⁹

Hindus divided ruby into four castes, calling the true Oriental ruby a Brahmin, and possession of a Brahmin was believed to give perfect safety, according to the Gemological Institute of America. Ancient Hindus believed that those who offered fine rubies to the god Krishna were granted rebirth as emperors. People in India believed that rubies enabled their owners to live in peace with their enemies.¹³

Burmese warriors believed ruby made them invincible in battle, and warriors inserted rubies into their flesh. The reports of this practice are attributed to early Burmese warriors by the GIA. Ruby has been called the most precious of the 12 stones created by God, according to the Gemological Institute of America.²¹³¹²

Ruby became one of the most sought-after gems of European royalty and the upper classes after the birth of the western world. Many medieval Europeans wore rubies, which were believed to guarantee health, wealth, wisdom and success in love. In 2015 a 25.59-carat ruby ring sold at auction for $1,266,901 per carat, a new auction record for a colored gemstone.¹³²³

Rubies are mentioned four times in the Bible, in association with attributes like beauty and wisdom, according to the Gemological Institute of America. It is improbable, however, that ruby was known to the ancient Hebrews. In gem-producing nations such as Sri Lanka, pink colours were always considered ruby, while in many consuming countries they are classified as pink sapphire.¹³¹¹¹

Birthstone, zodiac and chakra links

Ruby is the birthstone for July, a link the GIA gives on its birthstone list. Crystal practitioners repeat the July link as a modern tradition.³²

Ruby is the gem for the 15th and 40th anniversaries, according to the GIA. Crystal practitioners associate ruby with the root, heart and sacral chakras, and this chakra link is modern, following the New Age practice of mapping stones onto the body's energy centres.³²

What crystal practitioners say

Practitioners associate ruby with the mind and emotions. Crystal healers say ruby sharpens instincts, clears emotional stagnation and fuels inner fire. Crystal practitioners describe the stone as one of life force energy that inspires confidence and devotion. Ruby is described as a stone of love and protection that encourages living fully and courageously.

Ruby is regarded as a talisman of wisdom and health for the wearer, according to crystal practitioners. Ruby practitioners say the stone builds physical vitality, courage and confidence, and grounds the user into the body. As a symbol of passion, ruby is regarded as an ideal romantic gift by the GIA.¹³

Crystal practitioners say ruby can be cleansed by passing it through a candle flame or smoke, or by sunlight charging after rinsing. Practitioners further recommend placing ruby in an elixir made with the indirect method, with 4-6 drops taken under the tongue.

What testing has found

Reviewing 150 complementary and alternative treatments, Edzard Ernst reported that no rigorous trials have tested whether crystal healing has therapeutic value. He also concluded that no scientific evidence shows any benefit beyond placebo. Even so, he regarded the practice as generally harmless and non-toxic.¹⁴

In 2001, British psychologist Christopher French tested 80 volunteers who held and meditated with crystals, asking them to distinguish genuine stones from imitations. Those holding fake crystals reported impressions similar to those holding real ones, a result that points toward a possible placebo explanation.¹⁴

Jarry argues that people who feel better after using crystals may be experiencing regression to the mean, self-limiting conditions or misremembering, and that their testimonials create an illusion that crystals work. Pleasant feelings or seeming successes of crystal healing can be attributed to the strong placebo effect and to believers' cognitive bias.¹⁴