From Kat Von D, the solid perfume ring for her recent Saint & Sinner fragrances (shown above left). Comes with two interchangeable pans and a velvet pouch, $30.
From Michael Kors, a solid perfume ring in Very Hollywood Michael Kors (shown above right). $40.
And from Marc Jacobs, the ring for Marc Jacobs Lola. $42 with matching pouch.
All three rings are in size 7 and can be found at Sephora.