Ellie
9ct yellow gold narrow inlay ring
Inlaid with own slate
Estimated size K (to be confirmed with 3D printed rings)
2.5mm wide
Same profile as platinum example you saw
£950
 
Ian
Damascus steel - dense twist pattern
Single channel inlay ring
Inlaid with own slate
Estimated size Q (to be confirmed with 3D printed rings) 
6mm wide
Flat profile
£319
 
I estimate this work would take around 4 months given current workloads, but more time is always appreciated to space things out and leave plenty of time.
 
Above costs are complete and include all labour, materials, sizing rings and hallmarking for the gold ring.