If not sure if there is a crack, but the chip up to a light. Cracks, even those filled, are usually easy to spot

Here is such an example (Union Club, Cuba) from my website:

Most all of the UC 50s have cracks in the ring. No 100s I know of have a crack. The reason is that for some reason the makers of the chips chose to cut the ivory for the 50s much thinner. The chips are near 2# in diameter.