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The Diamond Resorts credit card is a Mastercard and thus can be used anywhere Mastercard is accepted, and Mastercard is accepted everywhere around the globe, so you won't have any problems. However, if you think about rewards redemptions, things are not that easy. You can redeem your rewards as statement credit towards Diamond Resorts purchases as well airfare and car rental purchases, provided those purchases are more than $50.
If this is limiting to you, you may try regular rewards credit cards. They allow you to redeem rewards for any purchases, some of them work like regular cash back cards.