Flat band with 4mm princess cut, bezel set white diamond in sterling silver or 9ct yellow, white or rose gold
6mm wide by 2.5mm thick.
Inlaid horsehair flat braid or short hair/fur/ashes set in crystal resin 3mm channel
Diamonds are available in many colours, if you prefer a coloured stone please contact me for options/pricing.

Last pic is an example of a bezel setting from the side so you can see the height above the ring.
Hallmarked
Rings are made to measure, I send a ring sizer out when an order is placed.