“The world is blue at its edges and in its depths,” wrote author Rebecca Solnit, a declaration that lends weight to the intrinsic appeal of the sapphire—September’s official birthstone. This enigmatic blue gem represents a transitional time of year, when the last few days of summer shine before autumn arrives. Commonly mined in Australia, Madagascar, and the United States, the sapphire is one of the most durable natural materials on earth—in fact, the only gem strong enough to scratch a sapphire is a diamond. Perhaps that’s why, notably in the Victorian era, the sapphire (which also symbolizes sincerity and faithfulness) was the preferred jewel for engagement rings—a trend that has resurfaced in recent years. Although widely known for being midnight blue, sapphires in bright pink, yellow, orange, and green are also part of the gem’s family. Here, we have chosen seven sapphire designs from five designers that show this captivating stone’s true range.