Kate was spotted wearing this necklace at the Cuckoo Club in August 2006.
Here is a close up of the pendant.
I’m not sure if this is solid gold or gold plated. Kate has proven that she doesn’t mind wearing gold plated jewelry, so this could be gold plated costume jewelry. The heart pendant looks to be raised and three dimensional. I don’t think it’s a flat and thin pendant.
This is the only photo I can find with Kate wearing this. If anyone can find more photos at different outings, please send me the link.