Ruby
THE PHYSICAL AND OPTICAL PROPERTIES OF RUBY
Ruby is the red version of a mineral called corundum, which also includes sapphire. The red, sometimes pinkish or brownish color of ruby corundum is due to the presence of chromium. It is the fourth hardest mineral (index 9 on the Mohs scale), after diamond, lonsdaleite and moissanite. Its density varies between 3.97 and 4.05. It is an aluminum oxide with the formula Al2 O3. Its luster is vitreous, greasy, matte, and it is transparent to translucent. Its fracture is conchoidal, splintering. Of rhombohedral crystalline system, it occurs in crystals, grainy aggregates, and pebbles. Its pleochroism is red-orange and purple. Its fluorescence shows a carmine red.
THE COLORS OF RUBY
The ruby used in jewelry ranges from red verging on pink (rubies from Burma) to slightly orange-red (like those from Tanzania). But the ruby mineral can be shaded with brown or purplish. All other colors of corundum are categorized as sapphire. 
THE GENESIS OF RUBY AND ITS MAIN DEPOSITS
Ruby is a very rare mineral. It can be of magmatic origin or, most often metamorphic, that is to say that it results from the modification of pre-existing rocks under the effect of heat and high pressure. Its appearance requires the presence of aluminum, silica, and a little chromium for the color… Only 1% of the rubies found have the characteristics required to be used in jewelry.
Today, 90% of rubies come from Burma: they are of exceptional quality and have magnificent nuances. Sri Lanka and Thailand are also important suppliers. There are also deposits in Africa, America and Australia.
Purity is an important criterion of value. All rubies have inclusions, this is not a defect, but the purest stones are obviously the most expensive, the price of ruby jewelry can fly off if the stone weighs more than 2 carats.
The most sought-after color is an intense and deep red, even if it does not belong to the "pigeon blood" category, which is very rare (a few tens of thousands of euros per carat). This term is often misused. Know that the brilliance and depth of the ruby will appear even more in the evening, under the effect of the lamps, than in broad daylight.
The ruby is generally cut in oval, sometimes in cushion or in pear, more rarely in round.
A common and totally accepted practice is to heat rubies to enhance their color. Without this, natural gems turn pink and are not very transparent. There is no downside to buying a stone that has been heated; moreover the naturally very intense stones have extremely high prices.
STORIES AND LEGENDS AROUND THE RUBY
The word ruby comes from the Latin "ruber, red."
The rarity and beauty of ruby, brought to Europe by the Etruscans and Greeks around 500 BC, have made it an extremely precious stone since antiquity. She is often quoted in the Bible, as in the Book of Isaiah (54), which says, speaking of Jerusalem as the Lord's bride: "I will found you on sapphires, I will make you battlements of rubies, your gates of stones sparkling”.
In the Middle Ages, the ruby symbolized the blood of Christ and kings wore it on their crowns as a sign of their faith. It is said that a ruby crossed the centuries from the Roman Emperor Augustus, of whom it was the seal, to the kings of France...
The ruby was an important gemstone in the Hindu religion. It was one of the nine stones representing the planets that influenced the world and was attached to the sun. In ancient India, the discovery of a beautiful ruby gave rise to imposing ceremonies and the stone was consecrated to Krishna.
VIRTUES AND BENEFITS OF RUBY
From Antiquity, the ruby was linked to the health of the heart, it was even believed to be able to protect against lightning!
Today, in lithotherapy, it is used to help treat heart and circulatory problems. Its action is so powerful that it should be avoided by hypertensive people... That said, it would also have the ability to regulate female cycles, and to fight against fever and infections, even against poisons.
Apart from its curative virtues against physical dysfunctions, the ruby would provide many psychological and spiritual benefits. It would prevent nightmares and anxiety. It would bring good luck and suit energetic and ambitious people. It would darken or tarnish in case of danger… and it would even prevent infidelity in the couple!
In oriental wisdom, the ruby is linked to the 4th chakra, that of the heart. It could promote the development of distance vision, facilitate meditation and spiritual enlightenment. In all traditions we find a common point, happiness in all its forms...
ASTROLOGICAL CORRESPONDENCES OF THE RUBY
Ruby is the stone associated with the sign of Leo (July 22 to August 23). Its flamboyant color reflects the conquering, passionate and proud character of Leo. In Chinese astrology, it would be the stone of the Dog and would symbolize courage, victory, love and happiness. The ruby would bring good luck to people born in July, and the ruby wedding designates the 35 years of marriage.
The Science of Ruby
Ruby is what gemologists consider to be the red brother of sapphire, for they have the exact same base composition – a form of aluminum oxide called corundum – and they differ exclusively on their coloration, being every red corundum considered a ruby, while corundum of any other color is labeled as a sapphire. Depending on the concentration of chromium, titanium, vanadium and iron in the stone, ruby gets its pinkish to dark red tonality, and just like sapphires, these are some of the hardest substances on the Mohs scale.
Rubies are mined and traded mostly in Thailand and Burma, but recent discoveries in Madagascar made the country become one of the main exporters of rubies.
It has a trigonal hexagonal scalenohedral crystal system and a Mohs hardness of 9.
Ruby throughout History
Taking its name from the Latin word rubens , it literally translates as “red”, and rubies definitely are the kings of all red gemstones.
During the Middle Ages, rubies were considered the most effective shield against one's misfortune on all levels, be it related to love, finances or health – rubies would ensure that one's fate would turn in the most positive of ways.
While India was one of the most important locations for some of the best and more expensive rubies, it received the Sanskrit name of ratnaraj , meaning “The King of all gemstones”, for they believed it was created when Mother Earth's blood crystalized.
Those who'd have the financial power to offer rubies in honor of Krishna believed that in their next life they'd reincarnate as an emperor.
Like every great gemstone, rubies were mentioned and highly regarded in virtually all ancient religious texts, from the Christian Bible to the Hindu religious writings.
Ruby's healing properties
This fiery red gemstone gifts its bearer with love, self-respect, courage to pursue his dreams and loyalty to his loved ones.
Rubies are considered to be basilar for those who live exhausting and intensive lives and, therefore, find it extremely hard to keep a strong and clear focus on the tasks at hands, for their minds are working on full throttle and rational concentration only becomes possible when a ruby enters their lives.
Being a stone of true wisdom and clear perspective, rubies ensure that one's path is not paved with countless bad turns and tremendous time losses due to wrong decisions.
A ruby will make its bearer find a sincere increase in productivity and have a true will to let go of all destructive patterns that lead to problems in the past.
Those feeling like they're an easy target for the evil eye or others' harmful intentions can greatly benefit from ruby's powerful shield that guards its bearer against any mental or physical attack.
ruby care
Even without much profound care, a ruby will endure for much more than a lifetime. However, a long exposure to a strong heat or light source can affect its delightful tonalities, so due care should be taken.
In order to wash a ruby, warm and soapy water (or a mild dishwashing detergent) and a soft brush should be all that's needed for its royal beauty to keep shining proudly.