My Godmother gave me a pearl necklace that was worn by the bridesmaids at my mom's wedding 20 years ago. She said they are real but I am not so sure, they are really tiny and have a rainbow shine to them I have a picture of them what do you think? Also they are on a regular old string not on a chain.http://c4.ac-images.myspacecdn.com/images02/131/l_0069c6b6506b4b78ad1825fc574e1617.jpg

They look like "wild" freshwater pearls, due to the irregular shapes and the colour you described.
The more easily recognise sphere pearls are cultivated and rigorously quality control for standards of size and shape.

Personally I prefer the freshwater variety as they are formed naturally rather than forced.
Pearls benefit from handling as the natural oils in your hands, etc give them their lustre.

I have a necklace that looks almost exactly the same.
Mine are natural pearls, they aren't worth a lot but are very pretty. Mine are also on what appears to be just a cotton string.

You could always just pop into a jewellery store and ask their opinion.