Hi this jewelry mark doesn't necessarily mean the necklace is made of gold. It could be some kind of trademark. Just because the metal is gold colored doesn't mean it's made of GOLD.
If there is not gold standard mark and you think it might be gold then have it tested. If you can't get an image, what I'd suggest, is to take the necklace down to your local jeweler you know and trust and ask for their opinion. If you don't know a jeweler you can trust, the decorative arts department at your local university, college or jewelry workshop, etc. should be able to point you in the right direction.
