Long before pearls were cultivated they were very rare and costly. As a result of this imitation pearls have been around, at least since the days of the Romans, and all the way through the Middle Ages, the Renaissance to the present time. Especially when the style of the day for some royalty was to cover their garments completely in pearls, did they use imitation pearls. Today, imitation pearls are worn by anyone looking for a substitute for real pearls. 

I guess that it is because of the difficulty in imitating the luster of the natural pearl, that recipes for imitation pearls have been very interesting. Recipes for imitation pearls have differed throughout the ages; but, none of the  recipes seem to be something that would make one want to wear them if the recipe was known to the wearer. One very popular recipe was to grind up small seed pearls, glass and fish bones.Then you nadd snail slime(mmmmm, yummy) and egg whites to hold it all together. After that the paste was put into molds, pierced with a hogs bristle and baked in the belly of a fish. What? No eye of nnewt?

Supposedly Leonardo da Vinci had his own recipe. which entailed dissolving pearls in lemon juice, making a paste from this concoction, drying the paste to a powder and mixing with egg white. Shape them and put them in a small lathe and polish them with a dogs tooth. I am forever curious as to why they were so specific in those day. Like, would the imitation pearls turn out poorly if a cows tooth was used?

In the seventeenth century, a Frenchman, who was a rosary maker, came up with a very ingenius technique to manufacture imitation pearls of very good quality. He used fish scales that had a high degree of luster, ground them up and mixed the scales with laquer toproduce essence d'orient. He filled small hollow glass beads with this mixture. This formula is still used today except now the glass beads are solid and coated with the mix. 

Imitation pearls are very different from real pearls, first in weight, either much heavier or much lighter. Next is the surface itself, which in the imitation pearl is verysmooth and not at all uneven like a thing made by nature. There are two well known  techniques for checking to see if the pearls are real. They are probably as old as imitation pearls themslves. The first technique is to rub two pearls together, if they are real they will feel not exactly smooth but have some resistance to the sliding motion. The second way is to rub the pearl across the front of your mteeth, that will give you the same result, if real they will feel kind of gritty and if imitaion the feeling will be very smooth or slick. And, then of course the X-ray is proof positve of their genuiness.