# over their heads

"over the heads of the living creatures"

# was the likeness of a throne

"was something that looked like a throne"

# sapphire

a very valuable stone that is clear blue and very shiny

# on the likeness of the throne was

"on what looked like a throne there was"

# a likeness like the appearance of a man

"something that looked similar to what appeared to be a man". This probably refers to Yahweh. See Ezekiel 1:3.