New Art Glass Signed to OrderBy

New Art Glass Signed to Order

Your Choice of Tiffany, Steuben, Quezal, and More

A seller using the internet auction site offered to sign reproduction art glass with the buyer's choice of marks. Winning bidders were offered their choice of Tiffany, Steuben, Quezal and others. The seller also regularly offered reproduction art glass with imitation marks already applied.

Although the seller clearly states the glass is a reproduction, the seller also stresses how the new pieces are based on originals and how accurately they duplicate the look of originals. The offer to sign pieces is equally as blunt and clear. Here are some typical descriptions.

Main title listing: Tiffany/Steuben Style JIP Aurene Vase. After describing a jack in pulpit style vase the seller states, "It is unsigned but can be so as the buyer designates."

Main title listing: Tiffany/Steuben Style Blue Aurene Vase. After describing a floriform vase the seller states "It is unsigned and the choice will be left to the buyer."

Main title listing: Tiffany/Quezal Style Floriform Vase. After describing a floriform with pulled feather pattern the seller states, "This piece is mint and unsigned. It can be if the buyer wishes but we will leave that to the buyer's discretion." Are these new pieces a threat? To find out, ACRN purchased two samples from this seller's fixed price web site to compare the new glass and signatures to originals. One new sample was signed "Steuben", the other was signed "Tiffany".

How To Evaluate Art Glass

There are a number of potential clues to help you authenticate and date art glass including 1) shape, 2) glass quality and finishing, 3) iridescence, and 4) markings and signatures. We'll consider each of these features in a step-by-step comparison. Keep in mind, however, that no one single test will provide conclusive proof of age or authenticity. Examine many features before deciding whether a piece is new or old.

SHAPE The majority of new glass offered on this seller's fixed price web site and eBay auctions copies the shapes of old originals. ACRN's sample new Steuben (Fig. 4), for example, is a direct copy of the genuine Steuben shape 2564 ((Fig. 5). The old shape number is even included as part of the new mark. Since old shapes are being copied, shape alone is not a reliable indicator of age. Shape is still a consideration, however, because some bidders are able to choose which signatures they want applied. Steuben shapes obviously should not have Tiffany signatures.

Steuben shapes are the easiest to document because of precise record keeping. Tiffany and other companies kept less accurate records but are still fairly easy to document. See the end of this article for books with authentic shapes.

Glass Quality & Finishing

The vast majority of all authentic 19th and early 20th century art glass has a polished or ground out pontil. (See Figs. 6 & 8). Pontils on the reproductions are rarely ground out or polished. If you encounter a piece marked or signed with the name of a well known art glass maker such as Tiffany, Steuben, Quezal, etc., and the piece does not have a ground pontil, it is almost certain to be a forgery.

On the other hand, the presence of a ground pontil is not a guarantee of age. In a final review of this seller's site before going to press, several pieces were described with ground bases. Grinding pontils is also a service most antique glass repair services can perform. ACRN has had several pontils ground in the past by such services for $10-$20 each.

Another way to check for quality work is to look at the smoothness of the glass surface. Original art glass with solid iridescent surfaces (excluding pulled feather and other worked in designs) virtually always have perfectly smooth surfaces. Both of our examples from this supplier had obvious waves, ripples and streaks in the glass itself. This was particularly apparent in the surface of the new Steuben piece (Fig. 9, pg. 32). The surface was so irregular as to create slight shadows in the miniature hills and valleys. Streaks and swirls were also present but to a lesser extent in the new Tiffany piece. The irregularities were easily felt by touch in both examples. These surface flaws are in the glass, not in the iridescent finish.

One of the easiest tests for overall glass quality is to simply hold a suspected piece to the light. Many art glass reproductions will show obvious streaks, swirls, bubbles and sometimes even impurities like cinders or unmelted sand in the body glass. Although such flaws are hidden from casual view by the iridescent coating, they are easily seen when held to the light. Any of those flaws almost always indicate a reproduction.


The rainbow iridescence on new and old art glass is created by spraying the glass with various metallic coatings. The exact effect depends on the amount of spray, how it is applied and how long it is heat treated. The basic colors of iridescence – blue or gold – are determined by the chemicals dissolved in the spray.

Practically all original solid color iridescent finishes like Steuben Aurene and standard Tiffany Favrile are silky to the touch and almost perfectly uniform in density. This means the iridescence appears as a smooth continuous coating without any exposed non-iridized glass or any pits or bubbles in the iridescent coating. The exception to this rule is when the glass itself is manipulated after the coating. If a rim was crimped or flared, for example, after being iridized, the iridescent coating would "crack" and the body glass would show through. But this is considered an artistic and a desirable effect.

Generally speaking, iridescence on American Art Glass like Steuben and Tiffany is either all glossy or all matte finish2. Gloss and matte finishes were virtually never combined in authentic originals. Problems with iridescent finishes are almost all caused by mistakes in applying the metallic sprays.

Iridescence on reproductions varies in quality; some of it is quite well done, some very poor in quality. The most common problem with new iridescence is the inconsistent finish. Random mirror-like reflections commonly appear in otherwise satin or matte surfaces. The general appearance can range widely within one piece. Our new Tiffany vase, for example, has oil-spot iridescence on the foot, pronounced vertical streaks on the sides and a cloudy swirled effect around the top third of the vase.

Iridescence on the new Steuben piece varies considerably. There are numerous spots where the iridescence is very thin and the base glass shows through. Random streaking and cloudiness are common over all the surface.

A particularly good area to inspect the iridescence is the bottom of the piece. Generally speaking, the iridescence on the bottom of originals is a perfect match for iridescence on the entire piece. In the majority of reproductions we've handled, the bottom is almost always different. In both our new samples, particularly the Tiffany piece, the bottoms are have a strong mirror like reflection while the overall iridescence is matte finish.


The most important rule to remember about markings is this: "Never buy a piece based on the mark alone". Why? First, marks are no guarantee of age because they are so easily forged. If you focus on the mark alone and don't study how the glass is made, you'll eventually own fakes and reproductions with forged marks. Second, depending on maker, not all originals were marked. If you refuse to buy unmarked items, you will pass up some excellent examples. However, since authentic marks do increase the market value of a piece, it is extremely important to know and understand what original marks are appropriate for the different styles and manufacturers of glass.

The vast majority of authentic marks on iridescent American art glass were engraved by a rotating wheel. Engraved numbers and letters have a ragged edged shaky or jerky look as shown in Figs. 10 & 11. This is because only the very edge of the wheel made contact with the glass. Wheel engraved authentic marks usually have a frosted, dull appearance although this will vary with the depth of the grinding.

Marks on the new pieces from this particular seller are engraved as well but with modern carbide or diamond tipped tools, not wheels. These modern tool bits produce a continuous flowing line with a smooth, clean edge (Fig. 13). The diamond and carbide tips actually cut– rather than grind– the glass and the new marks are less likely to appear frosted. The small tips cut through the iridescence revealing the body glass below.

Original wheel engraved marks are generally, but not always, smaller than forged marks. Numbers and letters in original Tiffany marks for example, are rarely taller than one-quarter inch; most are one-eighth or three-sixteenths. Marks from any maker with letters over one-half inch high are suspicious.

There are no "standard" marks for any of the original companies. Marks were applied by many different workers as needed. The names and words used in marks varied. Likewise there is no set or standard location for marks to appear. Many authentic marks, particularly Tiffany, run around the edge of the pontil but can appear in other areas as well. Tiffany date codes and Steuben shape numbers are widely forged and by themselves aren't a reliable test of age. And don't overlook the obvious. Many careless forgers often misspell Steuben, Aurene and Favrile.

Keep in mind there is considerable variation among original marks. There are many other forged marks besides the ones shown here. Use a variety of tests when evaluating age and authenticity.

1. A complete list of original 1903-1932 Steuben shapes is in The Glass of Frederick Carder by Paul Gardner © 1971 (out of print). A good basic book on Tiffany with 350 catalog photos is Tiffany's Glass Bronzes Lamps, R. Koch © 1978.

2. Some European art glass combines matte and gloss iridescence, notably Loetz.


Fig. 1 New signature on "Steuben" reproduction. Marked "Aurene 2564". Also note large broken pontil mark (clear glass.)


Fig. 2 New signature on "Tiffany" reproduction. Marked LC "Tiffany Favrile 3343B". Note large broken pontil mark (arrow).


Fig. 3 New 11″ vase signed "Tiffany" as in Fig. 2.


Fig. 4 New "Stueben" vase, gold Aurene finish over Calcite body; 11″ high, top rim 5¾″ dia. A copy of an original shape.


Fig. 5 Original #2564 shape vase as shown in 1903-1932 Steuben shape book. This shape was copied for the reproduction in Fig. 4


Fig. 6

Before a piece of blown glass can be decorated and finished, it must be removed from the blow pipe. This is done by using a pontil rod with a small amount of hot glass on the end. This end is joined to the partially shaped blown glass on the blow pipe. Once the pontil rod is attached to the blown glass, the blow pipe is removed. Now the blown glass receives its final shape and decoration. After allowing the piece to cool slightly, the pontil rod is snapped or "cracked" off leaving a small lump of rough glass, or pontil mark, on the base of the blown glass. When the piece is annealed and completely cooled, the pontil mark is ground off and may be polished.


Fig. 7 View of new Tiffany base. The pontil rod has been cracked off leaving the rough pontil mark in the center.


Fig. 8 Close up view of typical polished out pontil.


Fig. 9 The glass below the iridescent surface of the new Steuben piece is wavy and rough. Area above shown about actual size.


Fig. 10 Original wheel engraved marks are generally quite small. This original Tiffany mark, "L C Tiffany Favrile 1838" fits within a 1″ diameter polished pontil. Note the original paper label.


Fig. 11 Genuine wheel engraved mark. Actual size about 3/16″ high.


Fig. 12 Wheels like these are attached to hand held rotating shafts or fixed arbors.


Fig. 13 Continuous smooth edged new engraved mark made with diamond or carbide grinders. Actual size about ¼″ high.


Fig. 14 Modern engraving bits that produce smooth edged numbers and letters in the new marks and signatures. These new bits actually cut the glass. The the old wheels only ground the surface.

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