What to send with the sketch
Send a sketch or reference photo, the ring size, band width, metal and finish, stone type and size, and the quantity you plan to order. Mark which dimensions are fixed and which are open.
References should show the detail you care about, such as setting style, shoulder profile or surface texture, rather than a general mood.
From sketch to CAD
A dimensioned CAD file is normally ready within about 48 hours after the brief is accepted. The render is reviewed for proportion and setting before a casting prototype is made.
Revisions are cheapest at CAD stage. Once a mold exists, changes mean a new mold or hand rework.
Design limits to plan for
Minimum metal thickness is set by casting and wear; very thin shanks and fine prongs are the first parts to fail. Stone size has to suit the band width, and engraving needs a flat area with enough depth.
If a design needs a feature outside those limits, the solution is usually a small design change rather than a stronger process.