I would choose a bigger tiffany 4-prong pendant, at least 0.23ct and cartier sapphire necklace. I am not a fan of key pendant and think it would look better in big size an long chain as 30' at least. 3 necklaces worn together, at different lengths, would be easily get tangled and it could be very annoyed sometimes 
I am petite with 5'3" and 105lbs, and 0.23ct diamond look very delicate and discreet on me. I choose 4-prong vs dbty as it does not look like labeled "tiffany" but I could still enjoy the tiffany craftsmanship. I will try to take a mode pic of my 0.23ct later when I get home for you.

I am petite with 5'3" and 105lbs, and 0.23ct diamond look very delicate and discreet on me. I choose 4-prong vs dbty as it does not look like labeled "tiffany" but I could still enjoy the tiffany craftsmanship. I will try to take a mode pic of my 0.23ct later when I get home for you.