When we talked to the vet about putting Ares to sleep, I asked them specifically about his remains. Not sure if you know this or not but they can do a group cremation or private cremation. In other words, a bunch of animals are cremated at one time and you get ashes from it (this is cheaper). We opted for the private cremation as we wanted to be sure we had only Ares' ashes.
The vet gave us a nice mahogany box with his name on it that contained his remains. We want to spread them in a few of his favorite places. I also received this necklace in the mail that contains some of the remains. I wanted to share as I think it's a great way to keep your dog with you at all times. I haven't put Ares remains in it yet but I plan to soon.