The name ruby comes from the Latin “rubeus” or “ruber” meaning red, and is one of the most precious and rare stones in the world.
Ruby is one of the traditional cardinal stones for jewellery making, along with amethyst, sapphire, emerald and diamond.
The gemstone rubeus – red in Latin – signifies the courage to exist in the world and also the fact that it wears an accessory of great refinement, a symbol present in the look of great leaders and consumers of articles in exclusive versions.
Ruby is the name given to the deep red variety of a mineral, corundum, which itself, under the name sapphire, can be any colour except red, which is the exclusive colour of ruby.
All samples of corundum lack the necessary qualities of transparency and colour to be considered gemstones.
For a long time it was called “carbuncle” and confused with red spinel and pyrope garnet. It wasn’t until the 1800s that it was added to the corundum group along with sapphire.
It is a blood-red colour with a hint of blue, with notable hues, one of which is called “pigeon’s blood” and is the most prized.
Names such as Siamese ruby or Burmese ruby refer only to the colour and not to the intrinsic quality.
It often contains inclusions (minerals, liquids…) which do not affect the quality of the gemstone, but guarantee its authenticity compared to synthetic stones.
If they are rutile, the ruby acquires a silky appearance when cut into cabochons; these tiny rutile needles create an asterism or cat’s eye, depending on the cutting orientation.
The presence of chromium modifies the colour, which, when cut into ribbons or veins, takes on a brownish hue due to the iron, which is not appreciated.
To speak of rubies is to speak of Burma, where the most beautiful rubies in the world have been mined and are still being produced, and where the Indian princes and marajas were in love with them.
Rubies are mined in Africa, Asia and Australia. They are most commonly found in Myanmar, Sri Lanka and Thailand, but can also be found in Montana and South Carolina in the United States.
In Brazil, rubies can be found in states such as Santa Catarina and Bahia, but the occurrence is low and the gemological value is nowhere near that of gems from Asian soils.
Pedra Rubi - Caracteristicas, Cores e Lapidação
Sometimes they occur with spinels in the same geological formations, leading to confusion between the two species: however, good specimens of red spinels have a value close to that of rubies.
Ruby gemstones are valued according to various characteristics including size, colour, clarity and cut.
Artificial rubies, on the other hand, cannot contain any imperfections.
Some manufactured rubies have substances added to them so that they can be identified as artificial, but most require gemological testing to determine their origin.
The largest star ruby in the world is the Rajaratna, which weighs 495g.
Ruby names used in the marketplace
- Burmese or Oriental – generally considered the best colour, traditionally referred to as Pigeon Blood (red to slightly purplish red with medium hue and vivid saturation).
- Beef Blood – slightly darker than Pigeon Blood
- French or cherry – slightly lighter than pigeon blood
- Thai, Siamese or Siamese colour, also called muddy ruby – (dark red to brownish red or purplish red)
- Ceylon or Sri Lanka – (light in colour) often lighter than Burmese or Thai gems
- African (Umba River) – typically orange-red in colour
Characteristics of Ruby
Ruby (aluminium oxide) has mineral characteristics that make it one of the 5 most valuable gemstones in the world, depending on its origin, cut and colour.
All natural rubies contain imperfections ranging from conchoidal to irregular with a vitreous lustre.
1. Hardness
Corundums (rubies and sapphires) are the hardest stones after diamonds, with a hardness of 9 on the Mohs scale.
2. Colour
Knowing the colour of the ruby stone from which a piece of jewellery is made is fundamental to identifying its value, as well as its origin and the natural characteristics that formed it, in the case of those of mineral origin.
The main colour of ruby is red, due to the chromium, and the most sought after colour is pigeon blood red.
So if you want to recognise the value of a ruby, you should know that the red colour of the gemstone should not be too light or too dark, as in these cases the gemstone loses its characteristic lustre.
Therefore, when buying a ruby pendant, for example, make sure that it is bright, colourful and, above all, certified.
3. Transparency
From transparent to opaque.
4. Lapidation
The mineral corundum gives rise to micro-crystals with a hexagonal (trigonal) shape and vitreous appearance found in basalts, gravels and marbles. The cabochon cut is often used, but it is also found in mixed and oval faceted cuts.
5. Possible treatments
Heating followed by controlled cooling, heating and slow cooling, diffusion (heat treatment above 1900ºC in the presence of titanium oxide or other colouring agent), heat treatment, oil staining, filling of voids and fractures with glass.
6. Possible confusions
Synthetic ruby, red garnet, chrysoberyl, natural or synthetic spinel, sapphire doublet with synthetic ruby, natural ruby doublet and garnet and glass doublet.
7. Natural vs Synthetic Rubies
Many people have doubts about the different types of rubies and it is important to know that while there are natural stones that are extracted from corundum, there are also uniquely beautiful synthetic rubies, alternatives that will appeal to jewellery lovers.
While natural gemstones are carefully extracted, synthetic rubies are engineered to achieve a lustre and colour that matches the aesthetic characteristics of these products.
See Identifying a gemstone or precious stone is a difficult task.
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