The number increases as the season advances until in November, in order to protect the young fish from the approaching winter cold, the stones lying in very shallow water are removed with the adhering oysters to deeper water—over six feet. After three years the oysters are taken out and the nuclei of the culture pearl inserted. This done, they are spread over the sea bottom, about one to every square foot and left undisturbed for four years. They are then taken out and opened and both the culture pearls and whatever natural pearls there may be, are harvested. At present, upwards of a quarter of a million oysters are treated annually. Experiments are being made constantly, in the United States and Europe, to improve upon the hollow glass bead lined with fish-scale but so far without success. The finest of these imitate the natural pearl very well and if finely mounted similar to the genuine, will deceive many while worn. Closer observation will reveal the glassy shine of the surface and it will be found under the loup to contain numerous small holes. The specific gravity is also less. One finds occasionally in lots, a mock-pearl which has been cut and polished from the mother-of-pearl, but imitations of this character are scarce and find no place in the market. The few made are found usually in parcels of fresh-water pearls and are put there by unscrupulous dealers, as also are hematite balls and even buckshot, to be sold with the lot by weight as genuine pearls. Since the price of pearls has advanced so rapidly, much ingenuity has been shown in the improvement of poor pearls. Button pearls grown to the shell are broken out and the under or flat side carefully scraped and smoothed to hide the irregular lines of juncture between the pearl and the shell. Protuberances on the surface of round pearls are scraped off and the broken skin edges smoothed down so as to be unnoticeable to the naked eye. In a like manner chalky rings and spots are toned down. Surface cracks are filled by soaking the pearls in a solution and if the pearl has been pierced, interior cracks can also be rendered unobservable. A serious objection to pierced pearls arises from the ease with which interior defects can be doctored where the skin is pierced and a boring made through the nacreous layers. Not only are cracks made to disappear, but coloring matter can be introduced between the skins. A white pearl of very poor color can by such means be changed temporarily into a black pearl which will command a fancy price. This illegitimate doctoring of pearls, whereby defects are hidden and a fictitious appearance of quality imparted to last long enough to make sales at exorbitant prices, should not be confounded with the legitimate improvement of pearls which is now growing to be an industry of some importance. Experts are now able by careful manipulation to restore to some extent the luster which has been lost by wear or age.