1933 C.F. Martin & Co. D-28

Authenticating a 1933 D-28 demands rigorous expert verification, as only 41 were made. Serial numbers for 1933 fall approximately in the 52,500-55,000 range — Martin's sequential records are exceptionally complete and should be consulted directly. The bracing must be scalloped X-pattern in Adirondack spruce, joined with hot hide glue; inspect through the soundhole with a mirror to confirm the characteristic thinned, scalloped profile of each brace. The top is Adirondack spruce, identifiable by its wider grain spacing and slightly pinkish hue compared to later Sitka tops. Back and sides are Brazilian rosewood with deep chocolate-purple coloring, dramatic figuring, and a waxy feel — fundamentally different from Indian rosewood's uniform brown. The herringbone purfling around the top is made of tiny inlaid wood strips forming a zigzag pattern; it should show age-appropriate wear and patina consistent with 90+ years. Binding is grained ivoroid, which yellows naturally with age. The neck profile is a substantial V-shape in mahogany with no volute at the headstock junction. The ebony fingerboard has small pearl dot inlays at standard positions. Tuners should be open-back Grover Sta-Tite with butterbean-style knobs — any enclosed tuners indicate replacements. The interior paper label and neck block stamp should show the C.F. Martin & Co. Nazareth, PA designation in the period-correct font. The finish must be nitrocellulose lacquer with age-appropriate checking (fine craze lines throughout). Red flags include polyurethane or thick refinish, a belly bridge that sits proud of the top surface (indicating replacement), modern white glue visible on braces, or a neck block with bolt holes from a modern neck reset. Compared to the 1931, the 1933 shows a slightly more refined body shape and the neck-to-body joint is more standardized as Martin settled into the dreadnought design.