Hi IvorySnow!
I think wearing gold and silver jewellery together is fine! As long as they are both not strong pieces in their own right. I normally wear a chunky silver ethnic cuff with a very fine gold necklace and it doesn't clash at all. I sell jewellery at www.tinglow.etsy.com
http://www.tinglow.etsy.com and I like to think my gold and silver jewellery can be mixed and matched. I think if there is a piece of jewellery which is very wearable (for example a necklace you wear everyday), you can pretty much pair it with anything gold or silver.
Hope that helps!
Tx