Sculpting

[Delta]

Hi guys,
I was playing Breath of Fire II ages ago and for some reason decided to look into it again a few days ago, and what fascinated me was an item from that game, the Dragon's Tear. In the game, it is a pendant worn by the main character which keeps you informed about the intentions of the people you talk to.
http://spriters-resource.com/snes/breathfire2/sheet/6665
Since I liked the design of it, I wanted to hold something like it in my hands, and maybe even be able to wear it. But how could I replicate it? I thought I should maybe try my hand at sculpting something like that. I have never sculpted anything before and my artistic skills are just about nil, so it would be a pretty daunting task, since it is not the most simple design ever made. But I see it as a challenge, which is why I am giving it a go nevertheless.
My plan to realize it is kinda strange as well, to say the least. At least I believe it would be fairly unorthodox. I am currently building a rough sculpt in play dough, which I then intend to make a cast of which will then be used to cast something in a more conventional modelling clay or stuff like that. Keep in mind I am a beginner at stuff like this and do not have any proper tool for the job, but this is as far as I have come as of today: