Anna, If it's just the clasp and not a total restring depends on the silver or gold clasp: Silver is $10 and gold is $30. If the clasp is strung into the necklace it will need to be restrung which is $4 an inch knotted on silk plus the clasp. Thank you, Joslin's
You will get a good honest price at joslins jewelry. Probably around $25.
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