Rather than a maker mark, perhaps a retailer's specialty line mark. Maybe RonJay is just meant to be RonJ. And here comes the longshots...since the design resembles bubbling water drops like ocean spray maybe accessory line carried by RonJon Surf Shops in the past. Not like their current stock, but they've been around since 1959. Perhaps an early line long since dropped. If your username implies Florida, this might be right from your own backyard.
Google search result for RonJay Buckle: "Ron Jay Silversmiths is a U.S.A. Government Contractor company, located at 25 W 47th St # 2, New York, New York, New York 10036." If the information is accurate, they are in the Buckles (Manufacturers), Fastener, Button, Needle, and Pin Manufacturing industry. Good luck if you choose to follow up on this.