There is a magic about blue stones, for their colour is a favourite with people of all nations and languages. This may be because, with the exception of the sky, there is not much real blue in Nature's colouring. There are not many blue flowers, and very few blue birds, fishes, and insects. But there are several blue minerals, and of these sapphires are the best and brightest.
The Oriental sapphire is the name commonly given to blue corundum. This stone is highly prized on account of its hardness, lustre, and transparency. It equals the ruby in hardness, in which quality it stands next to the diamond. It scratches all stones except the diamond, and a ruby has sometimes been scratched by a sapphire. But it differs from the ruby in several points. The ruby is usually coloured in a uniform manner, but the distribution of colour in a sapphire is most erratic. Then, if a ruby is exposed to strong heat its colour remains unaltered, but that of the sapphire will disappear under similar conditions, and this in spite of the fact that the stone itself remains the same and undamaged.
Sapphires are sometimes almost colourless, but are usually of an azure shade which at times verges on a blue-violet. In fact, every tint of blue, from the darkest to the palest, is represented in the sapphire, though an intense cornflower blue is the most admired shade of colour. Sapphires of large size and fine quality are far more common than rubies of the same description. As this is the case, there is far less difference between the price of large and small sapphires than between that of large and small rubies. At the present time a good sapphire costs from £8 to £10 a carat; but a flawless stone of a velvet lustre, deep blue colour, and perfect transparency is still rare, and has a price in proportion. One fine sapphire of 165 carats on view at the Paris Exhibtion of 1865 was sold for £8,000.
Some few sapphires of rare beauty and value are to be found in the various treasuries of Europe. In the collection of the Jardin des Plantes in Paris may be seen a rough stone of 132 1/16 carats known as the "Rospoli" sapphire, after the family who were once its owners. This is a most magnificent blue gem, free from all faults and patches. In the Hope collection was a large and valuable sapphire of the blue, velvety colour, which retains its beauty as well by artificial light as by daylight. This latter feature is, by the way, a test of quality, as the best Oriental sapphires keep their exquisite blue tint in the evening, while those of an inferior sort appear almost black by artificial light.
A beautiful sapphire, which weighs over 100 carats, belongs to the Duke of Devonshire. The lower portion of this stone is step-cut, while the upper part is cut as a brilliant. Many splendid sapphires can be seen at Court and in society. Our Royal ladies possess some splendid specimens, and the Duchess of Orleans, who is semi-royal, owns and wears a notable parure of sapphires and diamonds. Georgina, Countess of Dudley, has some priceless sapphires, which bear the brilliance of electric light to perfection. Lady Rossmore's sapphire and diamond crown is magnificent, and Mrs. W. K. D'arcy wears a wonderful necklace of very large sapphires set in fine brilliants. In this connection it may be said that jewellers always mount sapphires with diamonds, as the whiteness of the diamond is immensely increased by contact with the sapphire.
Sapphires are found in Burma, Siam, and Ceylon; in Montana and North Carolina, in the United States; and in the gold and diamond fields of Australia. The finest come from Siam, and the mines there have grown rapidly in importance. The sapphires in these parts are found in a sandy clay about two feet below the surface. Indeed, all sapphires are met with in sand and solid rock, and always in the same places as the ruby. There is not a single locality where one stone is found without the other; they are invariably associated.
The sapphires of Ceylon are not of high quality, but it is worthy of note that the island is famous for its great variety of gem-stones. And these include not only sapphires and rubies, but topazes, zircons, moonstones, amethysts, and tourmalines.
In Europe, sapphires occur in Saxony, and near the sources of the Iser river in Bohemia, but these stones are of no commercial importance.
Frauds are often practised in the selling of sapphires. The stones which may be most easily passed as sapphires are the blue topaz, blue" spinel, and blue tourmaline. All, however, differ from the true gem in the essential point of density. Most of the above-mentioned stones are much lighter, and will float in thick liquid, while the sapphire would at once sink heavily to the bottom. And, with the exception of the diamond, and now and then the ruby, all other stones are softer than the sapphire. Most of them can be easily scratched by a topaz. The blue tourmaline may be at once distinguished from the sapphire by its colour, which is an indigo blue, and not the blue of the cornflower.
Then, too, a device called a " doublet " is often used for fraudulent purposes. This is a sham stone composed of two pieces of crystal with a colour between; or-in better examples-thin layers of real stone faced by pieces of crystal, so as to appear as one perfect gem. These latter are constantly passed off as sapphires. But they may be distinguished from the genuine article partly by their colour, but best of all by a careful examination of the " girdle." Should the sapphire have been joined to an inferior stone the fraud will be at once detected. However, as has been said in previous articles, the surest test of a precious stone is its hardness.