What is that white ring on dogs nail?

my dog has a white ring on the end of his nail near the fur. Is that bone, I only found it on one nail.What is that white ring on dogs nail?
its lack of calcium, humans get it toWhat is that white ring on dogs nail?
Could be just a natural marking. Horses that have ';white socks'; sometimes have a much lighter hoof on that leg than their other legs. And I have a cat with mottled white on her feet. Some toes have white fur and light nails, and other toes have dark fur and black nails, even on the same paw.
it's a Miracle