Albert Barnes Commentary 2 Chronicles 3:6

"And he garnished the house with precious stones for beauty: and the gold was gold of Parvaim." — 2 Chronicles 3:6 (ASV)

Precious stones for beauty - This refers to gems, not marbles (compare to 1 Chronicles 29:2). The phrase translated “for beauty” means “for its beautification” or “to beautify it.”

Parvaim is probably the name of a place, but its location is quite uncertain.