From Paul Michael Design:

Who needs a key to your heart when you have The Sonic Solitaire? Embellish with your choice of colored stones that can represent almost anything, keep it true to Dr. Who colors, add a birthstone or go crazy and add a real diamond and make this “The Ring” using our custom settings.

It is much larger on the inside. This massively over engineered piece of Tardis jewelry will remind you daily that life is crazy! You have to enjoy it while you can. The spin Doctor is available in sterling silver, 14 karat white and yellow gold as well as platinum. A big and bold ring not for the timid.

[Source: Sonic Screwdriver Solitaire Ring | Spinning TARDIS Ring]