As coriander seed; not for colour, for that is black, but for shape and figure. Bdellium is either,
1. The gum of a tree, of a white and bright colour; or rather,
2. A gem or precious stone, as the Hebrew doctors take it; and particularly a pearl, as some render it, wherewith the manna doth manifestly agree both in its colour, which is white, Exodus 16:14, and in its figure, which is round. See more on Genesis 2:12.