The persons who devote themselves to this uncertain pursuit are chiefly Singhalese, and the season selected by them for "gemming" is between December and March, when the waters are low.[1] The poorer and least enterprising adventurers betake themselves to the beds of streams, but the most certain though the most costly course is to sink pits in the adjacent plains, which are consequently indented with such traces of recent explorers. The upper gravel is pierced, the covering crust is reached and broken through, and the nellan being shovelled into conical baskets and washed to free it from the sand, the residue is carefully searched for whatever rounded crystals and minute gems it may contain.
1: A very interesting account of Gems and Gem Searching, by Mr. WM. STEWART, appeared in the Colombo Observer for June, 1855.
It is strongly characteristic of the want of energy in the Singhalese, that although for centuries those alluvial plains and watercourses have been searched without ceasing, no attempt appears to have been made to explore the rocks themselves, in the debris of which the gems have been brought down by the rivers. Dr. Gygax says: "I found at Hima Pohura, on the south-eastern decline of the Pettigalle-Kanda, about the middle of the descent, a stratum of grey granite containing, with iron pyrites and molybdena, innumerable rubies from one-tenth to a fourth of an inch in diameter, and of a fine rose colour, but split and falling to powder. It is not an isolated bed of minerals, but a regular stratum extending probably to the same depth and distance as the other granite formations. I followed it as far as was practicable for close examination, but everywhere in the lower part of the valley I found it so decomposed that the hammer sunk in the rock, and even bamboos were growing on it. On the higher ground near some small round hills which intercept it, I found the rubies changed into brown corundum. Upon the hills themselves the trace was lost, and instead of a stratum there was merely a wild chaos of blocks of yellow granite. I carefully examined all the minerals which this stratum contains,—felspar, mica, and quartz molybdena, and iron pyrites,—and I found all similar to those I had previously got adhering to rough rubies offered for sale at Colombo. I firmly believe that in such strata the rubies of Ceylon are originally found, and that those in the white and blue clay at Ballangodde and Ratnapoora are but secondary deposits. I am further inclined to believe that these extend over the whole island, although often intercepted and changed in their direction by the rising of the yellow granite." It is highly probable that the finest rubies are to be found in them, perfect and unchanged by decomposition; and that they are to be obtained by opening a regular mine in the rock like the ruby mine of Badakshan in Bactria described by Sir Alexander Burnes. Dr. Gygax adds that having often received the minerals of this stratum with the crystals perfect, he has reason to believe that places are known to the natives where such mines might be opened with confidence of success.
Rubies both crystalline and amorphous are also found in a particular stratum of dolomite at Bullatotte and Badulla, in which there is a peculiar copper-coloured mica with metallic lustre. Star rubies, the "asteria" of Pliny (so called from their containing a movable six-rayed star), are to be had at Ratnapoora and for very trifling sums. The blue tinge which detracts from the value of the pure ruby, whose colour should resemble "pigeon's blood," is removed by the Singhalese, by enveloping the stone in the lime of a calcined shell and exposing it to a high heat. Spinel of extremely beautiful colours is found in the bed of the Mahawelli-ganga at Kandy, and from the locality it has obtained the name of Candite.
It is strange that although the sapphire is found in all this region in greater quantity than the ruby, it has never yet been discovered in the original matrix, and the small fragments which sometimes occur in dolomite show that there it is but a deposit. From its exquisite colour and the size in which it is commonly found, it forms by far the most valuable gem of the island. A piece which was dug out of the alluvium within a few miles of Ratnapoora in 1853, was purchased by a Moor at Colombo, in whose hands it was valued at upwards of four thousand pounds.
The original site of the oriental topaz is equally unknown with that of the sapphire. The Singhalese rightly believe them to be the same stone only differing in colour, and crystals are said to be obtained with one portion yellow and the other blue.
Garnets of inferior quality are common in the gneiss, but finer ones are found in the hornblende rocks.
Cinnamon-stone (which is properly a variety of garnet) is so extremely abundant, that vast rocks containing it in profusion exist in many places, especially in the alluvium around Matura; and at Belligam, a few miles east from Point-de-Galle, a vast detached rock is so largely composed of cinnamon-stones that it is carried off in lumps for the purpose of extracting and polishing them.
The Cat's-eye is one of the jewels of which the Singhalese are especially proud, from a belief that it is only found in their island; but in this I apprehend they are misinformed, as specimens of equal merit have been brought from Quilon and Cochin on the southern coast of Hindostan. The cat's-eye is a greenish translucent quartz, and when cut en cabochon it presents a moving internal reflection which is ascribed to the presence of filaments of asbestos. Its perfection is estimated by the natives in proportion to the narrowness and sharpness of the ray and the pure olive-tint of the ground over which it plays.