Chrysoberyl is a very hard gem mineral (only diamond, ruby or sapphire are harder). It comes in three colours - yellow, green and brown. Cat's-eye chrysoberyl can be cut, as here, to show a bright line with the appearance of the eye of a cat.
This ring forms part of a collection of 154 gems bequeathed to the V&A by the Reverend Chauncy Hare Townshend, a cleric and poet. Sir A. H. Church gave additional specimens in 1913. He also compiled the first catalogue Precious Stones: A Guide to the Townshend Collection. The first edition appeared in 1883. The stones are mounted as rings, although they may not have been intended to be worn.
Some of these, including this stone, were originally owned by Henry Philip Hope, a brother of the novelist and antiquary Thomas Hope. H.P. Hope formed a famous collection of diamonds and precious stones which was largely inherited by his three nephews. His collection, which included the Hope blue diamond, is now in the Smithsonian Institution, Washington.