The safest first answer to “what is this set?” is a good description. Identification grows from several clues together: the tile count, physical construction, decoration, marks, case, accessories, and any papers that remained with it.
Photograph the set as received
Before sorting, photograph the closed case, each tray, every compartment, labels, closures, and loose papers. Then make overall photographs of tile faces, backs, and edges in neutral daylight. These images preserve context that can disappear as soon as the set is reorganized.
Make a literal inventory
Count what is present without deciding what should be present. Record suits, winds, dragons, flowers, seasons, jokers, blanks, spare tiles, dice, counters, racks, wind indicators, and booklets separately.
A mismatch is information. A replacement tile, homemade label, or later joker can reveal how a set remained in play.
Describe construction—not just color
Ask whether each tile is one piece or laminated. Record the color and texture of the face, back, and side; whether decoration is carved, engraved, molded, or printed; and the approximate dimensions and weight of several tiles.
Museum collections demonstrate why construction matters. The British Museum catalogs a set made from bone, bamboo, and pigment, while the Smithsonian catalogs a set with laminated celluloid tops, bamboo backs, and cellulose nitrate components. Similar-looking sets can therefore involve very different materials.
A material name is a conclusion. Color, seams, translucency, weight, and tool marks are observations.
Record every mark and paper
Photograph maker names, retailer labels, patent numbers, import marks, stamps, pencil notes, and the title pages or copyright pages of rules. Search exact wording in quotation marks. A dated booklet may establish only that the booklet is that old—not necessarily every component of the set.
Avoid destructive tests
Do not apply a hot pin, flame, solvent, or scratch test. These can permanently damage a tile and can create unsafe fumes. If a high-stakes attribution depends on material identification, consult a qualified objects conservator or analytical specialist.
Form a provisional description
Write a restrained catalog line before attempting value:
Mahjong set, maker unknown, probably early-to-mid 20th century; laminated light faces on dark backs; 148 tiles plus accessories; housed in a fitted wood case; material attribution unconfirmed.
That line can change as evidence improves. Good identification is comfortable with revision.