Matthew Poole and continuators on Revelation 21:19

19 And the foundations of the wall of the city were garnished with all manner of precious stones p. The first foundation was a jasper; the second, a sapphire; the third, a chalcedonie; the fourth, an emerauld.

By which we noted before, are to be understood the Apostles, who building upon the one Foundation Christ Jesus, by their Holy Doctrine laid the beginnings of the Gospel-Churches, the first Stones (upon the Rock Christ) which were afterwards multiplied, others being builded upon them, till the whole Church was perfected.