Mother of pearl necklaces or pendants are made of a material called mother of pearl also known as Nacre which is a naturally-occurring organic-inorganic composite.
The iridescent appearance of the nacre is due to the way that the platelets are arranged and this results in different colors of light being reflected at different viewing angles. The iridescent inner layer is considered highly attractive by many cultures and is often used in making jewelery and watch dials as found in Rolex watches.
There are many different colors and hues of mother of pearl. Picking the one that is right for you is most important. In addition selecting what is to go with it, pearls, diamonds, or perhaps a different mother of pearl, as well as the style and design of the jewelery is most important.
If you have a design flair then designing what you want would be the first step. Then getting a jeweler to make up the design to your specifications. Alternatively simply looking around for something that you feel suits you best may be the way to go.
In any event the first step is in knowing what you want and what sort of design and jewelery you are comfortable with.
Gold usually goes very well with mother of pearl and a hardened gold such as 14 karat is ideal. It is not pure gold but has had other metal, such as copper, zinc and sometimes silver added to increase its hardness and make it more durable. Stirling silver is also good. It is about 95 percent silver with some copper or nickel added and this increases the silvers durability also.
Pearls go well with mother of pearl as does diamonds and other gemstones such as rubies, emeralds, sapphires for example.
A good search around, especially online, will give some good examples of what can be done with mother of pearl necklaces or pendants.
Plenty of patient searching and some due diligence will ensure that you find the mother of pearl necklaces or pendants that you are looking for.