This is the hole - the escape route for a lost ring. Please please please package metal jewelry properly when sending it through the mail. The machines make impressions of the piece on the envelope and either A. can tear right through the paper or B. send a message to a dishonest employee that says "hey, this looks like a ring!"
You can see more photos on flickr of the indention made in the envelope, well, several indentations actually, as the ring slide around.
Fortunately and unfortunately, the ring was not one of mine, but a customers ring they were sending me that they liked the size and fit and wanted to make sure their new ring would fit the same.... I was panicked and distraught. Luckily, sort of, it wasn't a particularly special ring, like a family heirloom or priceless diamond. sigh. but still. Please, package carefully.
I'm a full time artist - mostly in jewelry but I consider myself an all around artist as I love painting, photography, ceramics, and screenprinting. My business has largely turned in to making custom wedding rings which is wonderfully meaningful. I'm also a yoga teacher!