Albert Barnes Commentary 1 Chronicles 29:8

"And they with whom [precious] stones were found gave them to the treasure of the house of Jehovah, under the hand of Jehiel the Gershonite." — 1 Chronicles 29:8 (ASV)

Compare to Exodus 35:27. The same spirit prevailed now as when the tabernacle was set up. Each person offered what they had that was most precious.