Peeled pearls and maker mark

by Virginia
(Inwood, WV, USA)

This 16 in. strand of pearls has 4 pearls (out of 46) that someone has attempted to peel. Why would anyone do that? It was purchased at a flea market many years ago for the clasp, which I thought was sterling but turns out to be marked on the clasp insert, 14 kt. and a capital M that looks like it has tiny wings or short downward lines coming off the top of the M.

Impossible to photograph well with my limited skill and camera, but I tried. Is this a known mark? The peeled portion of the pearls looks dull until you turn it in light, when it has the glow of MOP and a layered appearance. Obviously they are not glass and the peeling did not reveal the nucleus I would expect for a cultured pearl. The strand weighs 28 grams or 1 oz. and 6 of them are about 5 cm long. The knots are small. The tiny bead tips look very old and brassy. Any information you can give me would be appreciated.