Which other jewelry company does Kay Jewelers' owner have? 
ULTRA Diamonds:  After its acquisition by Signet Jewelers, ULTRA Diamonds stores were re-branded as Kay Jewelers. Sterling Jewelers:  Sterling Jewelers is a wholly owned subsidiary of UK-based Signet Jewelers Limited (listed on the New York Stock Exchange under the symbol SIG), having been acquired in 1987.
Sterling Jewelers