"In heaven the semblance of a rainbow encircles the throne and overarches the head of Christ. The prophet says, “As the appearance of the bow that is in the cloud in the day of rain, so was the appearance of the brightness round about [the throne]. This was the appearance of the likeness of the glory of Jehovah.” Ezekiel 1:28 . The revelator declares, “Behold, a throne was set in heaven, and one sat on the throne.... There was a rainbow round about the throne, in sight like unto an emerald.” Revelation 4:2, 3 . When man by his great wickedness invites the divine judgments, the Saviour, interceding with the Father in his behalf, points to the bow in the clouds, to the rainbow around the throne and above His own head, as a token of the mercy of God toward the repentant sinner. PP 107.1"
"As the appearance of the bow that is in the cloud in the day of rain, so was the appearance of the brightness round about. This was the appearance of the likeness of the glory of the Lord. And when I saw it, I fell upon my face, and I heard a voice of one that spake."
EGW directly quotes Ezekiel 1:28 to describe the rainbow around the throne in heaven.
"And he that sat was to look upon like a jasper and a sardine stone: and there was a rainbow round about the throne, in sight like unto an emerald."
EGW directly quotes Revelation 4:3 to describe the rainbow around the throne in heaven.