I wrote a guide on buying jade on line and feel i should also write one on coral and turquoise items being sold as well.  Having 30+ years in the antique and estate jewelry business, especially in the area of Asian antiques, i can pretty much say that the vast majority of items made of these material and available from China are not, repeat, not real.  Having contacted a number of sellers selling these items, they all state that the item is hand carved, antique and of natural material.  Lies!!  The majority of these items are either a plastic compostion that is molded or is a polymer coated item that is the same thing.  When looking at the item check the pictures of the carving carefully, hand carved items will show sharp edges in the detail, molded items show rounded, smooth details, also, if you are seeing more than one item exactly the same then wake up and smell the coffee!  Real antiques were not made on an assembly line so that thousands were made so they could survive to the modern era.  There are factories in China that make thousands of these statues and pieces of jewelry including beads and pendants, they are experts at faking age on new items.  Look at the material, natural stone has flaws and variations in color and texture, fakes are even and show no flaws, if you find something that is real, check it out carefully so you can remember what it looks like when you look at the fakes.  Additionally, look at the price, just like jade, quality is reflected in price or value.  Face facts, the chance of getting an antique piece of carved coral or turquoise for 99 cents is rather rare, while there are bargains on eBay, they are from reputable sellers who are honest about what they are selling.  I feel that eBay is remiss in allowing these sellers to cheat people the way they do, but if you look at the lists of items you will see that the majority of these items do not sell, take a hint, people in the know do not buy them, they are there for the guilable.  If you want these items for the decorative value or for fun then be my guest but do not believe that you are buying some rare antique when you buy these items.  Be sharp and read carefully, be smart shoppers.