Hard to say without getting a good look at the shell, but the way the mantle looks and the little bit of shell I do see, it looks a lot like a squamosa. If that's the case, then you've got quite the find there, since blue squamosas are harder to find and usually more expensive.
I have to tell ya I love having clams they are close to my fave coral I use to have a 75g reef like 4 years ago that crashed and I had two in that tank here is a pic of the shells I still keep them in my coral skeleton collection