That is a very thin layer of the most valuable precious metal over solid 10k gold. This has a brilliant shine like chrome or freshly polished sterling, vs a yellowish white gold.
Almost every high end or designer white gold item is rhodium plated.
ALL jewelry clasps with any type of spring mechanism do in fact use STEEL springs.
It is the only material that is strong enough and can retain its memory.
Therefore they will be magnetic.
Stamped 10k
Outside Diameter: 6mm+Jump Ring & Trigger
Inside diameter: 3.00mm
Ring gauge: 15gauge
Jump Ring OD: 3.30mm
Jump Ring ID: 1.90mm
Jump Ring ga: 20gauge
Weight: 0.122 DWT or0.19 grams TWICE the weight of Standard ones