Well, ok, to be honest, I don't know what makes a perfect ring but have you sometimes experienced the difficulty of closing a jump ring?
It's like no matter how, there's this little gap hanging, which I think is rather common in 'cold connection' cases.
Alright, just in case you are wondering, 'cold connections' means no heat is involved in connecting pieces together. In traditionally silversmithing, jump rings are meant to be soldered in which case there's probably not such a big deal with minor gap. I think!
Anyway, this is something I picked up during the Beginners' Silversmithing class. Well, it wasn't taught to me literally but just something I observed and reckon how it's done.
So, okay, in circumstances like this, what you do is to reopen the ring.
Alright, now I give you a top view of how it's actually going to be reopen.
As you open the ring as you normally would, at the same time, apply pressure on the sides by pusing the two ends towards each other.
In other words, as one hand pushes one side of the jump to the back and another hand pulling another side to the front, simultaneously with the strength of your palm pushes the two sides towards each other.
I'm not sure if I'll be able to make them clear in words but I did try with drawing arrows on the picture which I hope would be better illustration.
What we're trying to do is kinda to get the ends to be slightly overlapping on each other.
Compared to how we would normally do it where both ends are more or less in tandem with each other?
Now, try closing it again.
As you pushed the two sides closer to each other, you'll see that the two ends of the jump ring overlaps, but that's ok. Just try to 'push it in' nonetheless.
And you should be able to 'get rid' of the gap.
And now, back to the front view.
There you go!
Hope this works for you like it did for me. :)