Doug,

To be absolutely positive, you could seal them in something for a day or two...a baggie, or a plastic box, or something like that. After 24-48 hours open them and sniff. Most of our dice that have had the vinegar syndrome have darkened in color and have "imploded" (the sides kind of cave in). I'm not sure if any of our crystallized dice smelled like vinegar. But you want to be really sure!

If they were my dice, I'd do the clear nail polish trick. When I've done it in the past, I've done one side...let it dry overnight. Do another side...let it dry overnight. Do another side...let it dry overnight...until all sides are coated.

If you want to be extra cautious, do one side of one die first. Wait overnight. Then you can confirm that the polish dries well.
.