Open Reference Library → Colour reference and timeline. Combine maker, generic colour, name, historical code and year bounds. Missing dates remain possible matches, clearly marked unknown. Only explicit annual assessments produce coloured year segments; legacy first/last dates never imply continuous production. Year bounds select the assessment window. Follow a segment to its evidence. Read chronology help. Use the width slider and horizontal scrolling for longer timelines. Table and timeline PDF buttons require a separate export entitlement and use the same filters.
From Catalogue lookups, choose a generic or maker colour and Edit visuals. Generic colours hold one optional HEX; every maker colour can hold zero to five ordered values. Add, remove and move values; use either the picker or #RRGGBB text. Each opacity slider ranges from transparent (0%) to opaque (100%). Blank HEX values are not stored.
Swatches use a white background, a black diagonal X, then the chosen colours and opacities. Multiple values make ordered stripes. This is a visual aid, not a calibrated reproduction of glass. Maker records without HEX use their associated generic value, explicitly labelled Generic colour fallback. With no value at either level, a neutral placeholder appears.
A photograph is independent of HEX. Choose JPEG, PNG or WebP, adjust the square position and size, review the 128px preview, then save. The browser normalises orientation and reduces large photographs to 2048px. The server independently validates and decodes the upload, then stores only re-encoded PNG data. Remove or replace a sample, or recrop its safely retained original. Previous stored visual states remain in restricted database history and normal database backups.
Viewing and PDF generation use separate Reference Library policies; editing requires Manage Lookups. Visual editing does not rename colours, rewrite historical dates or change catalogue import/export formats. Administrators should back up the database before recovery, including visual history and photographic blobs.