Name the provider and scope
A full manufacturer overhaul, independent movement service, pressure test and simple regulation are different events. State who performed the work and what the invoice says was completed.
Record replaced components
New hands, dial, bezel, crown, crystal or movement parts may improve function while changing collector originality. Include the parts list and disclose whether removed components remain with the watch.
Do not promise a fixed premium
Recent service may support the upper condition band or reduce a buyer's reserve, but it rarely adds its full invoice cost to the resale price.
Treat missing history as uncertainty
An undocumented watch is not necessarily unserviced. Price a reasonable inspection or service reserve rather than converting missing paperwork into a dramatic claim.
Keep the evidence with the reference
Make sure invoices identify the watch sufficiently without publishing a full serial number. Store originals securely and share redacted copies during qualified review.