Nice pearl.
Atlantic Quahog (Mercenaria mercenaria) is often pronounced ko - hog.
Yours is very round, very uniform at the surface and distinctively purple. One terrific thing about pearls from quahogs is they are almost always immediately identifiable as such. Any mollusk can produce a purple pearl, but clams pearls present uniquely from pearls from abalone, oysters or mussels. The odds are rare, but considering tens of thousands consumed daily they are going to occur every day. Hence they're considered common.
At P-G we're reluctant to appraise value. These threads are more about identification and the stories surrounding their history or craft. Almost always, we'll suggest a finder retain their pearl as a keepsake. It's an experience most can only imagine.
That said, your piece should fetch a premium for size, shape, color and surface. Those are four very strong points. If it rolls in a straight line even better. How quahog pearls list and how pearls sell are very different things.
It's a terrific find. Thank you for sharing it with us.