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Identification Guide

Art glass signatures.
How to read what's on the base.

A maker-by-maker guide to signatures on Tiffany, Lalique, Daum, Steuben, Galle, and Loetz — plus what to watch for when signatures seem too good to be true.

Reading the Marks

Where signatures are found and what they mean

Signatures are the single most important clue to the identity of inherited art glass. A signed piece by a recognized maker can be worth thousands of dollars; the same piece without attribution often sells for a fraction of that. Signatures are also the easiest feature to fake, which makes careful reading — and healthy skepticism — essential. This guide covers the major signed makers, where their marks appear, and what authentic signatures look like.

Where signatures are found

Art glass signatures are almost always on the underside of the piece. The most common location is the polished pontil — the smooth, circular, ground-and-polished area at the center of the base where the pontil rod was attached during blowing. The signature is engraved, scratched, or acid-etched into the pontil or on the flat base surrounding it.

Other common locations include the foot rim (around the edge of the base), the inside of the foot (on footed pieces where the base is concave), and — occasionally — the shoulder or body of the piece, particularly on cameo glass where the signature may be worked into the decoration. Lamps are often signed on the metal base; the shade may carry its own signature near the aperture ring. Use strong angled light and a magnifying glass to examine every potential signature location before concluding a piece is unsigned.

Tiffany

Louis Comfort Tiffany's glass was produced from the 1890s into the 1930s. Tiffany pieces are typically signed in one of several forms: "L.C. Tiffany Favrile," "L.C.T.," "Louis C. Tiffany Favrile," or "Tiffany Studios New York" (usually on lamp bases and metalwork). The signature is usually lightly engraved or scratched into the base and accompanied by a catalogue number — letters and digits like "A1234" or "2045N."

Authentic Tiffany signatures have specific hand characteristics. Reproductions often have signatures that look either too careful (like a printed font) or too sloppy (obvious modern tool marks). The piece itself must also match Tiffany's iridescence, technique, and form from the attributed period. An expert can often identify a genuine Tiffany piece from the glass alone, before the signature is even considered.

Lalique

Lalique signatures break cleanly into two periods. Pre-1945 pieces, made during Rene Lalique's lifetime, are signed "R. Lalique" — often followed by "France" and sometimes a piece number. These pieces represent the highest tier of Lalique value. Signatures appear in acid-etched, molded, or engraved forms depending on the piece type and period. Post-1945 pieces, made after Rene's death by the Lalique firm under his son and successors, are signed "Lalique France" or simply "Lalique" with no "R" initial.

The presence or absence of the "R." is a major value indicator. An "R. Lalique" piece can sell for 10 to 50 times the price of a comparable post-1945 "Lalique France" piece. Collectors and specialists scrutinize Lalique signatures carefully because the difference in value creates strong incentive for fakery.

Daum Nancy

Daum Nancy signatures are usually acid-etched or engraved on the base. The signature reads "Daum Nancy" and is typically accompanied by a small cross of Lorraine — a double-barred cross that was the symbol of the historical Duchy of Lorraine in northeastern France. The signature style varies across periods and piece types. Cameo Daum pieces often incorporate the signature into the cameo decoration itself, sometimes near the base of the design rather than on the underside.

The cross of Lorraine is a strong Daum identifier when present, though variations exist. Post-war Daum pieces (from the 1960s forward) often have simpler engraved signatures. Period of production affects value substantially; early cameo work from the 1890s through the 1920s represents the top of the Daum market.

Emile Galle

Galle was one of the founders of French Art Nouveau glass and one of the most prolific signers. His signatures appear in many forms: carved into the cameo decoration, acid-etched onto the base, or engraved in a flowing script. A typical signature reads simply "Galle" in a stylized cursive.

After Galle's death in 1904, the firm continued producing glass under his name until 1936. Pieces made posthumously are marked with a star above the signature — this is an important distinction, as star-Galle pieces generally have lower values than pieces made during Galle's lifetime. The star is small and easy to miss; careful examination with magnification is worth the effort.

Steuben

Steuben Glass was founded in 1903 by Frederick Carder in Corning, New York. Carder-era Steuben (pre-1933) includes a range of art glass colors and techniques; these pieces are signed in various ways, often with an acid-etched "Steuben" fleur-de-lis or engraved script. Post-1933 Steuben — the clear crystal pieces the company became famous for — is typically signed with a diamond-engraved "Steuben" or the Steuben signature along with a designer's initials for important pieces.

Carder-era colored Steuben (Aurene, Cluthra, Verre de Soie) is generally more collectible than later clear crystal. The signature style and location help date pieces to specific Steuben periods.

Loetz

Loetz is the exception that proves the rule. The Austrian factory, active from about 1880 through the 1930s, signed only a small fraction of its output — primarily pieces made for export to the United States. Signed Loetz carries a lightly etched "Loetz Austria" on the base. The vast majority of Loetz is unsigned and must be attributed by style, technique, and decor pattern.

Unsigned Loetz is still valuable when attribution is solid. Specialists recognize Loetz decors — Phanomen, Medici, Cytisus, Papillon — that identify the factory beyond reasonable doubt. A Loetz piece attributed by a recognized expert or auction house can sell for thousands of dollars without ever carrying a signature.

Reproductions, fakes, and warning signs

Every major signed maker has been reproduced or faked. Tiffany lamps are the most commonly faked art glass category in the world — vast quantities of reproduction Tiffany-style lamps with added "L.C.T." signatures circulate in the secondary market. Lalique fakes focus on adding "R." to post-1945 signatures. Galle pieces have been faked by adding star-less signatures to star-Galle pieces to inflate value.

Warning signs include signatures that appear freshly engraved on otherwise worn pieces, signatures that seem too crisply executed or too perfectly placed, glass that does not match the maker's documented techniques, and pieces offered at prices that seem too low relative to genuine examples. When in doubt, have the piece examined before committing to a sale. The difference between a signed authentic piece and a faked piece is often tens of thousands of dollars.

Quick Reference

Photo Tip

Photograph the signature area against a dark cloth with strong angled light — shallow engraved signatures catch light at certain angles and vanish at others. Include a second photograph with the piece held up to show the signature against a light background. If a signature is present, photograph it both in context (full base) and close-up.

An Honest Take

What usually isn't valuable

Not every signed-looking piece has the value that signature might suggest. Knowing what signatures don't automatically mean helps set realistic expectations.

"Tiffany-style" unsigned lamps

Stained-glass lamps in the Tiffany style have been reproduced in volume since the 1960s. Most unsigned leaded-glass lamps found in estates are not Tiffany and have modest resale value regardless of age or apparent quality. Even signed lamps require expert authentication because the signature alone is not proof. A genuine Tiffany lamp is the exception, not the rule, among dragonfly-and-wisteria style table lamps in American estates.

Post-1945 Lalique in common forms

"Lalique France" pieces from the 1960s through the 1990s — small bowls, ashtrays, figurines — have very modest resale value today. Prices have softened significantly as the secondary market for mid-to-late-century Lalique has weakened. A signed Lalique frosted glass bird or small fish typically sells for $50 to $200. Exceptions exist for designer pieces and rare forms, but common post-1945 Lalique is common.

Murano-style unsigned glass

Decorative Italian glass in Murano style, made for the tourist and gift markets from the 1950s forward, is almost never signed. These pieces can be beautiful but are not from recognized Murano factories and typically sell for $25 to $150. The Murano market is sharply tiered: documented factory pieces with labels or etched marks are valuable; unmarked decorative glass is not.

Faked signatures on period pieces

Some unsigned period art glass has had fake signatures added to it. A piece that is genuinely from the right era but has a fraudulent Tiffany or Lalique signature is worth less than the same piece unsigned — because the fraud, once recognized, creates a cloud over the whole piece. If a signature looks freshly engraved or inconsistent with the apparent age of the glass, professional authentication is worth the trouble.

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Common Questions

Frequently asked about art glass signatures

Signatures on art glass are usually on the underside of the piece — on the polished pontil (the smooth round area at the center of the base), near the foot rim, or just inside the foot. Some makers signed under the base at an edge, which can be easy to miss without careful examination. Lamp pieces are often signed on the metal base rather than the shade; shades were sometimes marked near the aperture ring. Use strong angled light and a magnifying glass. Signatures can be tiny, shallow, and worn.
Tiffany signatures vary by period and piece type. Common forms include "L.C. Tiffany Favrile," "L.C.T.," "Louis C. Tiffany Favrile," and "Tiffany Studios New York." A number is often scratched or engraved alongside the signature, sometimes with letter prefixes. The signature is typically lightly engraved or scratched into the base — not a raised mark. Authentic Tiffany signatures have a specific character and hand; reproductions exist and can be difficult to distinguish without expert examination. Signature alone does not confirm authenticity.
"R. Lalique" signatures indicate pieces made during Rene Lalique's lifetime — roughly 1908 to his death in 1945. These are the most valuable Lalique pieces and regularly sell for thousands of dollars at auction. After 1945, pieces are signed "Lalique France" or simply "Lalique." Post-1945 Lalique is still collectible and has real value, but generally at lower levels than pre-1945 work. The distinction matters enormously to the market — an R. Lalique signature can represent a value difference of 10x or more compared to a post-1945 piece of similar form.
Daum Nancy pieces typically carry an acid-etched or engraved signature on the base reading "Daum Nancy" accompanied by a small cross of Lorraine — a double-barred cross that was the symbol of the historical Duchy of Lorraine. The signature is usually stylized and can vary across periods. Cameo Daum pieces often have the signature incorporated into the decoration rather than on the base. The presence of the cross of Lorraine is a strong indicator but not definitive; specialists verify signatures by comparing against documented examples and examining the glass itself.
Most Loetz glass was not signed. The Austrian factory produced iridescent art glass from the 1880s through the early 20th century but signed only a small portion of its output — typically pieces destined for export to the United States. Signed Loetz pieces carry a lightly etched "Loetz Austria" on the base. Most Loetz is attributed by style, technique, and form rather than signature. Specialists recognize specific Loetz decors — Phanomen, Medici, Cytisus — that identify the maker despite the lack of signature. Unsigned Loetz can still be very valuable when attribution is solid.
Yes, fake signatures are a persistent problem in the art glass market. Tiffany, Lalique, Daum, Galle, and Steuben have all been faked. Common techniques include acid-etching a fake signature onto an unsigned period piece, adding a signature to a later reproduction, and rubbing down genuine signatures from modest pieces to use as templates. A signature alone does not confirm authenticity — the glass itself must match the maker's techniques, colors, and forms from the attributed period. Expert authentication is essential before selling significant pieces. If a signature seems too perfectly placed or too crisply executed on an otherwise worn piece, that is a warning sign.