US Navy Support Facility Diego Garcia Challenge Coin. Size: Coin is 1 5/8 inches in diameter. General Information & Frequently Asked Questions – Please read before you message me. Please leave feedback & I will do the same for you! Please let me know if you have an issue and I will work hard at resolving it! If you are unhappy about the product or service you receive, please notify me before leaving feedback so I can have the opportunity to resolve the issue. I will not respond to any questions regarding this policy. For any questions not covered above.