EFFECT OF RADIUM ON PRECIOUS STONES.

Wairarapa Age, Volume XXXII, Issue 10146, 16 December 1910, Page 7

EFFECT OF RADIUM ON PRECIOUS STONES.

It is announced, says the Morning Post, on the authority of a fairly wide range of experiments, that radium will change the colour of precious stones. A few months ago a series of experiments were entered upon to discover the effects which radium, had on various precious stones. Mr Armbrecht, of London, conducted a number of experiments, the results of which are highly interesting. "I began my experiments," he said, "with white sapphire, which is pure oxide of aliminium. I placed a number of sapphires, about two hundred in all, in contact with pure radium. In the course of two or three weeks the greater number of them had turned yellow or orange. A few of them, which apparently came from another source, had turned a green, pinkish, or amethyst colour. I should say thai, roughly speaking, about 70 per cent, o the whole number had turned yellow, and the yellow varied from lemon to dark orange. Two or three of them turned very slightly blue, but not sufficiently'blue to take the colour j of the blue sapphire, the expensive I and fashionable colour. "By the use of radium I have managed to change very pale emeralds into emeralds of a darker green, but they are not sufficiently dark to equal the true green emerald, which is of considerable value. In experimenting with diamonds I have produced a clearer lighter colour ; in other words I have bleached a-brown diamond into white. I have not yet been able to obtain a blue diamond, ' but Sir William Crookes has a most beautiful blue-green speciman, which was originally a yellow stone. The I bleaching of the diamond is an easy process, but it requires a very long time. Again, an amethyst, under the influence of radium, may turn into a smoky topaz; or yellow topaz. '"I have also treated pearls, but have only been successful in cleaning a dirty looking pearl into a clearer white. Opals have not proved amenable to treatment. That failure was to bo expected, because the colour of the opal is produced by the reflection of light from the different laminae, or layers of the opal, just in the same way as the iridescence of the pearl is caused."