The One seated there looked like jasper and carnelian, and a rainbow that gleamed like an emerald encircled the throne. — Revelation 4:3

There's a rainbow around the throne like an emerald. That's the covenant promise — God's bow of mercy wrapped around His throne of judgment. God set the rainbow in the clouds as a sign of His covenant with every living creature. Of God's covenant, ordered in all things and secure. God made an oath to Abraham, backed by two unchangeable things — His promise and His oath — so that we who fled for refuge might have strong encouragement.