From my Samples, Singulars, and Somethings Completely Different collection -
I am not 100% certain, but it is very, very, very likely that this is a Windlass Steelcrafts main gauche, make and model number unknown. I got it alongside of a couple of circa 2000 Windlass swords, and while it does have an "INDIA" mark, it doesn't necessarily have to be Windlass, as there were other bits in the acquisition, too. I don't recognize this particular piece, but rapier and gauche were never my main interests - but I have asked a couple of rapier friends, so we may have the identification nailed down soon. Any way - a singular piece, and certainly not something you're likely to find elsewhere, from my collection to your collection.
blade: 15 3/4"
blade width: 1 3/8" at guard
blade width: 1/2" at 2" from tip
grip and pommel: 4 3/4"
guard: 6 3/4"
ring: 2 7/8 x 2"
weight: 10.8 oz