This connector has 2 soldered closed 3.5mm jump rings, one on each side.
Inside diameter of jump rings 1.5mm.
Most stones Plazko.com sells (in chains, charms, connectors, drops or other products) are enhanced with globally acceptable standards. Stones are commonly enhanced to improve their color, clarity and durability. There are many ways stones can be enhanced. Some of the most common enhancements are irradiation, heat treatment, vapor deposition, dyeing, filling and impregnation.