Ruby belongs to the corundum family of which all except red are known as sapphires, so rubies and sapphires have similar properties.
It is a gem highly valued for its scarcity, since the mines are almost depleted in the world and there is little production with good qualities, especially in large sizes.
In May 1995 a ring with a 16-carat ruby sold for $ 4 million at Sotheby’s auction house in Geneva.
- Hardness: 9 on the Mohs scale
- Specific gravity: 3.9 – 4.1
- Conchoid fracture
- Color: Intense red to violet or brown
- Vitreous shine, and can occasionally appear silky
- Variable transparency, and possible presence of inclusions that give a milky appearance.
Ruby producing countries
First of all, a clarification, since you have to differentiate between origin and provenance.
Origin means the country where the mine is located and origin is where it is marketed and handled. For example, we can have a ruby whose origin is a mine in Vietnam and its origin is Thailand because it is here where it has been carved and commercialized.
Thailand is the main ruby carving and trading country in the world, yet it hardly has a few small mines in Chantaburi. The main deposits of the world are in Burma (Myanmar); Sry Lanka; Vietnam, Cambodia; Madagascar and Mozambique.
Value a ruby
Rubies are valued based on their color, purity, size, and size.
- Colour: Unlike diamond, there is no color scale (only the GIA has an indicative scale), so there is great subjectivity in this regard. In principle, rubies with a slightly dark but transparent intense red color called “pigeon blood” would be the most valuable color, and as soon as it has purple tones, it loses value. losing transparency, so you have to find an intermediate between intense color and transparency. The light must pass sufficiently but at the same time allow an intense color. The lighting that is used when viewing the ruby is important. With sunlight the fluorescence is higher and the ruby appears redder. Ruby is said to be a gem at night as it looks very red in incandescent light.
To buy, the sun must not hit the stone fully. If red is visible in low light, it is because it has a good color.
- Purity: Regarding purity, we will say that since the ruby is rarer, the inclusions devalue it less than in other precious stones, although without a doubt the less there are and the purer the ruby is, it will also be more valuable.
- Size: Rubies generally come in oval or emerald cut. However large rubies cut into a round shape are generally more expensive because more material is wasted.
- Weight: The most valuable gems are generally between 3 and 5 carats in weight, although the law of supply and demand prevails in this case. From these weights the price is very subjective, and can be very high.
It is a 167-carat Burmese ruby donated by John Ruskin to the British Museum of Natural Sciences.
Ruby Roser Reeves:
An impressive example of a 138 carat star-effect ruby from Sri Lanka, currently owned by the Smithsonian Museum in Washington.