Maybe you could remind him that he already got you a diamond pendant and ask to exchange it.
I know that when I have been in your situation, I do want a special piece to remember milestone anniversaries. This year we are doing major reno to our bathroom so we went to Tiffany and got sterling silver. Almost immediately I was kicking myself for not getting a more milestone type of piece. I understand where you are. If you have been dropping hints and he's not responding it gets frustrating.
I know that when I have been in your situation, I do want a special piece to remember milestone anniversaries. This year we are doing major reno to our bathroom so we went to Tiffany and got sterling silver. Almost immediately I was kicking myself for not getting a more milestone type of piece. I understand where you are. If you have been dropping hints and he's not responding it gets frustrating.