From an unused root meaning to polish; a gem supposed to be jasper (from the resemblance in name) -- jasper.
H3471. yashepheh
יָָֽשְׁפֶה noun [masculine] jasper (loan-word from Persian so Arabic Lane2978, also (and on forms , ) Frey; perhaps Assyrian ašpû DlHA 36, HWB147) — וְיָָֽשְׁפֵ֑ה וְשֹׁהַם תַּרְשִׁישׁ Exodus 28:20; 39:13 (both P) beryl and onyx and jasper (see Di); וְיָָֽשְׁפֶ֔ה (+id.) Ezekiel 28:13 (see Sm).
יִשְׁמָּה see below שׁפה; יִשְׁמָּן see below שׁפן