From The Collaborative International Dictionary of English v.0.48:
Ouch \Ouch\ (ouch), n. [OE. ouch, nouche (a nouch being taken
for an ouch: cf. Adder), fr. OF. nusche, nosche, nousche,
buckle, clasp, LL. nusca, fr. OHG. nusca, nuscha.]
A socket or bezel holding a precious stone; hence, a jewel or
ornament worn on the person.
[1913 Webster]
A precious stone in a rich ouche. --Sir T.
Elyot.
[1913 Webster]
Your brooches, pearls, and ouches. --Shak.
[1913 Webster]