Ello everyone. I could use some crit, please.

[dpixel]

What was the direction of your light source? I had my source projecting from the top-left.

It was top left as well.  Note the specular highlight in the gem.

I feel as if, though, the shadows and shading are quite dramatic?

That's what high contrast will do.  Maybe I took it a bit far with this one,  but generally pixel art looks better with high contrast.

[Crit Nasty]

@ dpixel: My apologies, I was so focused on your method of contrast that I didn't notice your light source; it's definitely the top-left haha.

Is there a standard to the size of palette one should normally use with a 16x16 tile? IS this why you chose 10 (including transperancy)?

[dpixel]

Is there a standard to the size of palette one should normally use with a 16x16 tile? IS this why you chose 10 (including transperancy)?

I don't think there's any standard color count.  Although it seems like 16 colors is popular to pixel just about anything at any size.  For a 16x16 a lot less is needed. 
Low color count in pixel art is generally for your benefit.  It's just easier to keep track of especially when animating.  A lot of times adding extra colors that are close in value makes no difference because the eye can't really see them. 
For me and a lot of others, colors are one of the hardest things to get right...or be satisfied with, etc.   Usually new people use to much saturation and too low contrast.

Have a look at this:  http://pixeljoint.com/forum/forum_posts.asp?TID=10695
And this:  http://pixeljoint.com/forum/forum_posts.asp?TID=11299

if you haven't already.
 

[BatElite]

The problem seems to be that you're saving as .jpg, which introduces a lot of colours during compression. In the future use .png instead.

As for the ring itself, last update is certainly an improvement.
I'm not fond of the darker pixel on the outer edge. I assume they're there to make the edge stand out against the white background. I suggest working on a grey canvas.
Also, you should make the large gem either darker or brighter, as it blends in with the rest of the ring right now.

[Crit Nasty]

@ dpixel: I've reviewed both and they were extremely infomative. Thank you for sharing those resouces! I suppose I will try to limit my palette while attempting these 16x16s for good measure and practice. I could use a really good lesson or tutorial in animation if you know of any 

@ BatElite: Yes, thank you. while reading through the resources dpixel shared, there was a topic as to why to not save in .jpg and to save in either .gif or .png, as you mentioned. I appreciate your compliment and crinticism! And now that you mention it... I'm going to try to rework the edges to see if I can find a better value (is value the correct terminology?) for the AA.

Thank you two for your responses!