The appearance of the wheels and their work was like unto the colour of a beryl: and they four had one likeness: and their appearance and their work was as it were a wheel in the middle of a wheel.
The appearance of the wheels and their work - their form, and the material of their work.
The colour of a beryl - rather, 'the glancing appearance of the Tarshish-stone;' the chrysolite or topaz, brought from Tarshish, or Tartessus, in Spain. It was one of the gems in the breastplate of the high priest (Exodus 28:20; Song of Solomon 5:14; Daniel 10:6).
They four had one likeness. The similarity of the wheels to one another implies that there is no inequality in all God's works, that all have a beautiful analogy and proportion.