Invest knowledgeably in the Ruby, rare and much sought after | EN

There is no doubt that for the experts, the ruby is by far the most interesting stone as an investment. But, let us make it quite clear now, that it is also the most expensive. Generally speaking, the value of the ruby is twice as high as that of a diamond of the same weight. To give an idea of the prices currently ruling but still subject to strong upward tendencies - in the last year, the price of rubies went up by 200%! - It must be considered that a stone with a commercial quality of 1 to 3 carats costs between 1.500 and 9,000 dollars per carat; a beautiful 3 - carat gem is assessed on the basis of 17,000 dollars per carat, whilst the figure for a 5 to 8 - carat ruby of very beautiful quality reaches 50,000 dollars per carat.

But what is a beautiful ruby? The ruby is a variety of corundum, alumina (Al2 O3). It is not so hard as the diamond but, on the Mohs scale, it is nevertheless classified just behind it (9).
It belongs to the rhombohedrons crystalline system and its fracture is conchoidal. Its density oscillates between 3.96 and 4.10, and its refraction index is between 1.76 - 1.77. This pure crystallised alumina derives its name from " ruber ", which in Latin means red. It is a symbol of happiness and love, and it is said that it brings freedom goodness and authority to people born in July. Its colour ranges between reddish pink and deep purple, and it owes its fascinating tonal properties to its chrome oxide content (Cr2 O3). The most sought after stones are those, which are very limpid and have a deep luminous colour.
The "pigeon blood" ruby is well known, that noble red with a deep shade of carmine. This sumptuous colour is due to the presence of 0.1% chrome oxide in the stone mass.
As for the red-brown or purplish-blue, seen in other gems, it is explained by iron and vanadium traces. This is true, of the rubies of Siam, remarkable for the sombre palate of their tints. Without matching the attractive prestigious brilliance of Burmese rubies, they are still very high up the scale, especially when they happen to display that beautiful "pigeon blood" colour. The rarity of the latter is explained by the fact that chromium is not a particularly common element in the earth's crust.
From Burma to Sri Lanka
The most beautiful rubies come indisputably from the Burmese seams. The most important mines are in the Mogok valley, but they are very old, and their production methods have not been modernised. The absence of Government stability and authority has led to anarchical and irrational operation of the mineralogical centres.
Nationalisation has made no contribution whatsoever to the development of their extraction potential or to the dynamics of their performance. But to this economic drawback there is another, which has political overtones. The State of Burma does not permit the activity of precious-stone-export companies.
It takes upon itself the sale of rubies, by annual auction to foreign governments. Regretfully, there has been a noticeable decrease in the quality of gems over the year, together with a constant drop in volume of consignments coming on to the market.
One can understand therefore why Burmese rubies are more and more becoming the object of the covetous attentions of the connoisseurs.
Thailand, with its Chantabury seams, and Sri Lanka - formerly Ceylon - feature among the producer countries whose gems are also in demand. Not so long ago, the mines of Pailin in Cambodia were providing magnificent rubies. However, following the events, which threw that country into confusion, the mining centres, have discontinued their activities.
Asterism and spinel
Certain rubies bear evidence of asterism. They are fine inclusions of rutile, which produce a luminous star with six branches. The effect is particularly original and attractive. Cabochon - shaped, these stones reach very high prices. Finally, it will be remembered that there is a certain similarity between the ruby and the red spinel, but whereas, it is recalled, the former is of crystallized alumina, the second is a magnesium aluminate. Their colours may appear to be quite similar, but their prices bear no comparison with each other.
Here also, it is advisable to seek the knowledgeable opinion of an expert should there be any doubt. Not only is he very experienced in examining stones, but he also has a panoply of refined optical instruments, the use of which reassures the lay-man by a full analytical diagnosis.
Lets look at auctions for a few rubies:
May 2012 at Sotheby’s Geneva a oval ruby 7,66 ct sold at 151.397 us$ per carat.
December 2011 at Christie’s New York oval ruby 8,24 ct, sold at 512.925 us$ per/ct
November 2011 at Christie’s Hong Kong oval ruby 6,16 ct sold at 248.173 $/ct.
November 2011 at Christie’s Geneva oval ruby 8,11 ct sold at 283.481 $ per carat.