Smaller and inferior pearls are found in a land¬locked bay on the north-east coast of Ceylon, known as Lake Tampalakamam. Here, upon a dark grey-black mud intermixed with quartose sand, is found the Placuna oyster, with valves which, during the first year of its existence, are so transparent that one can see its whole anatomy, even to the beating of its heart. Read the rest of this entry »

Off the coasts of Venezuela the Spaniards, from the time they conquered the mainland, carried on pearl-fishing ; but towards the beginning of the eighteenth century this commerce was abandoned, and was only revived again in 1895. There, the oysters are collected by divers or by an implement called ” arrastra,” a small drag provided with a net into which the oysters fall as they are detached by the drag. Read the rest of this entry »

But all the stones or gems valued thus are not ex¬tracted from the earth. A few are found in strange places and have a more mysterious origin. Two of these deserve special attention, the pearl and amber. Read the rest of this entry »

Jadeite is not the pure jade, but possesses the colour which the Chinese fancy. As these people are the greatest purchasers of jade in the world there is a good commerce in the article. Jadeite is found in masses of interwoven crystals embedded in the laterite and serpentine rocks. Read the rest of this entry »

Another stone regarded with great superstition, but of good omen, deserves some notice. Jade is found in Asia and Oceania, and is celebrated for its toughness, and for its popularity, particularly among the Chinese. Read the rest of this entry »

The opal is a non-crystalline mineral of hydrated silica occasionally displaying a beautiful play of colour, hence its value as a gem stone. The precious or “noble” opal, as the real gem is called, is, however, but one variety, and is only found in a few places. Read the rest of this entry »

Besides the Oriental emerald, which, as previously mentioned, is a form of corundum, there is the ordinary emerald found in Peru, Columbia, Bolivia and Siberia. This is a variety of beryl, from which, however, it is distinguished by its colour of emerald green instead of pale green, light blue, yellow or white, the colours of the beryl. This shade of green is produced by the presence of chromium, those of the beryl arising princi¬pally from the presence of iron. The precious emerald is valued, in commerce, next to the ruby and diamond, sometimes before the latter.

The search for emeralds requires great patience and industry, for disappointment is more frequent than success. Often there is little or nothing to guide the prospector, the whole formation of black carbonaceous limestone being covered with earth to a depth of from six to thirty feet, as at Muzo and Cosquez in Columbia, where some beautiful gems are found embedded in. veins of calcite, the veins sometimes being less than six inches in depth.

The earth deposit, frequently covered with jungle, has to be removed before prospecting is possible, and a break may prove quite valueless after months of work have been expended upon it. Emeralds which are exposed in the course of quarry¬ing are carefully loosened and detached from the matrix by a ” pricker,” the other quarried material being broken up by light hammers in sorting sheds. The fragments of these remains are closely examined for gems. Some of the stones found thus can be picked out clean. Others have to be cleansed from the adhering matrix, by treatment with cold dilute hydro¬chloric acid.

Before being marketed, the emeralds are sorted into about fifteen different grades.
Emeralds have been found in different parts of the Andes since the sixteenth century, and the deposits around the district of Muzo, Columbia, previously mentioned, are believed to be inexhaustible, in spite of many disappointments.

The sapphire, the blue variety of corundum, is mentioned in the Bible as being the second stone in the second row of the high priest’s breastplate, and again in the Book of Job as a precious stone; but there is some doubt whether the modern sapphire is, in either place, referred to. Sapphire is usually found with the ruby and other forms of the corundum, but in Siam sapphire is more common than in Burma. Read the rest of this entry »

The sapphire, the blue variety of corundum, is mentioned in the Bible as being the second stone in the second row of the high priest’s breastplate, and again in the Book of Job as a precious stone; but there is some doubt whether the modern sapphire is, in either place, referred to. Sapphire is usually found with the ruby and other forms of the corundum, but in Siam sapphire is more common than in Burma.

The method of winning both gems from the surface gravel is similar and simple. The gravel is excavated and carried off in baskets by men working in small parties of three or four. In Burma, however, hydraulic machinery and other scientific improvements have been introduced, but this forms part of the romance of mining. After washing the gravel, the gems are picked out by hand, usually by Europeans, and sorted into about a dozen different qualities. The best come to the London market, the others are sold by atiction fortnightly to local dealers.

A large amount of corundum gems of inferior quality is used for making jewelled bearings of watches and for various electrical instruments ; a small amount is also used for wire-drawing. For such purposes colour and transparency are of little account, but the minerals must be pure, free from parting planes and must break with a conchoidal fracture. Over 20,000,000 of watch jewels are sold annually.

A large ruby is more valuable than a large diamond, weight for weight. Some experts affirm that a five-carat ruby is worth ten times as much as a five-carat dia¬mond. Certainly an eleven-carat ruby has been known to fetch £7000 sterling, while an eleven-carat diamond is estimated at only £1000 sterling in value. These were pre-war prices.

Rubies are found in Ceylon, Borneo, Kashmir, Siam. Afghanistan, Montana in the United States, and New South Wales, but only a few come from any of these places. The bulk of the rubies in commerce come from Mqgok, ninety miles north-east of Mandalay, the capital of Burma.

For three hundred years the Burmese kings, who loved the ” pigeon-blood ” stones, as they called them, owned the area of land upon which the rubies were found. The possession by any private individual of a ruby worth more than £70 was a crime, and the ruby-fields were forbidden ground to the stranger. Since Great Britain annexed Burma in 1885 these ruby-fields have been worked by an English company, on lease till 1932. The most valuable stone found here weighed 77 carats.