Hey,
As this is my first try at jewelry modeling and also my first try using Cycles I thought I’ll seek for your feedback and advice on the results I got so far. Feel free to be harsh! 
Thanks!
Very nice! What is your lighting set up? If you aren’t, you should try using an HDRI for your lighting as this will make the reflections much better.
I agree with Longaly: Reflective surfaces need something to reflect.
Plain environments will make reflections look… well, plain. And often reflections also help the eye tremendously to grasp the shape.
The attached images are far from being a perfect example for jewelry rendering, I just added them to make my point. The main difference between those two renders is the environment, all materials are exactly the same. See how much more vibrant the first render is? How the surface detail of the pendant is much more perceptible?
Also: Did you think of having a black instead of a white backdrop? Right now the silvery-white pendant IMHO gets a bit lost on the white floor with the strong reflection. I could also imagine the pendant lying on a piece of black velvet, with a chain attached. In jewelry photography you often see pendants shot in a hanging position, as that is the perspective a potential customer is most interested in.
And is there a rigid connection between the heart shape part and the loop that later gets attached to the chain (or whatever)? The intersection between those two parts looks a bit strange right now.
Please, take everything I wrote with a grain of salt, as I’m just a hobbyist myself and hardly know I’m doing anyway. And I’m just nitpicking on details: This is by all means a promising start.
And btw: Merry Christmas!
Attachments
Thank you guys!
You do make a point on the environment here… Actually, as you can see on the right side (the top of the heart and loop) I have that already in place. I wanted to go for a very unintrusive one and I now realize I overdid that 
I have been playing around with a dark background, mixed with a bit f glossy and some diffuse and that turned out indeed better.
The hanging position is indeed a common one and that with a reason. I’ll go give that a try, too!
Once again, thanks for taking the time to reply!
Merry Christmas to all of you!