It sounds as if the ring, unless specified in the will, is legally the property of your father. So the actual inheritance, etc may be irrelevant other than it may be relevant to the cost basis of the ring.
There are a couple of approaches, which are some4what complicated in that estate taxes (which are tied into gift taxes) for the future are up in the air:
1) Have your father sell the ring and report any gain on the sale as a capital gain (you will need to track down the basis in the ring- either original purchase price or value upon inheritance. With the latter, if you can do so the gain is often less in most circumstances). If you desire the proceeds then have him gift you the proceeds. He can give up to $13,000 a year to you and another $13,000 a year to your spouse (if you have one) without having to file a gift tax return. If you desire that he give you more in a given year then he can file a gift tax return and apply part of the estate exemption toward the gift tax (he won't pay a gift tax on it but it will reduce the amount of his estate that can be inherited tax free). If you want more than the $13,000 in a given year I would seriously consider option #2.
2) Have him gift you the ring and have you sell it. You would be responsible for the capital gains (again you need to track down the basis) and he would need to file a gift tax return as referenced in #1.
Adam Accountant Wilmington NC