eBay
Here's a 9K yellow Gold Pendant set with a lovely Green Tourmaline and with an Opal at its centre.
The main ring bale measures 0.5 inch or 13mm and the Tourmaline is 5/8 inch or 16mm long with
an Opal approx 0.2 by 0.1 inch or 6mm by 3mm set at the bottom of the ring bale                                There's no chain with this gem and it weighs 0.8g.
Photos were taken in natural light to get the true colours.
Any questions just ask- I'm not a Jeweller so I'll ask my Wife because its hers! 
Please note that because of eBay fees, PayPal fees and the included free postage and packing the price is the price and I can't change it.
Free UK postage included.
This is also listed for sale on Etsy so may just disappear from here.
Check out my other items for sale.