Record the profile clearly
Photograph the rim from above, the side and along the profile with a scale. Measure diameter only where enough curvature survives to justify an estimate, and label estimates as such. Support fragile fragments safely rather than balancing them on sharp edges.
Describe manufacturing evidence
Note visible seams, bubbles, color, tool marks and the relationship between rim and neck. Do not claim that bubbles prove ancient glass or that iridescence proves burial. Weathering can be altered or imitated, and later glassmaking also used many of the same basic forms.
Compare with excavated types
Use museum catalogs and archaeological publications containing secure context where available. List multiple possible comparisons when a fragment is ambiguous. A rim profile without a vessel body may fit several categories. Keep typological resemblance distinct from a claimed archaeological findspot.
Do not neglect provenance
Ask for ownership and lawful export or import records where relevant, including documentation of when the fragment was separated from its original context. If the seller cannot establish lawful history, a scholarly resemblance is not a reason to overlook the gap.
What to do next
- Photograph rim profile with a scale
- Keep estimated diameters clearly labeled
- Record manufacture and condition separately
- Compare published excavated examples
- Maintain independent ownership documentation
Common questions
Does iridescence authenticate Roman glass?
No. Iridescence is not by itself proof of date or provenance.
Can one rim fragment reveal a precise date?
Usually not; typological ranges and uncertainty should be recorded.
Cultural-property compliance varies by jurisdiction. Style and seller documents do not establish lawful title. Obtain independent professional advice and avoid inadequately documented material.