FAKED SPIRAL GLASSES
Fraudulent air-spiral or cotton-spiral-stemmed glasses, not engraved or inscribed, are the fraud most often offered to a collector: in addition to the other tests mentioned, the test of the skill and quality of the spiral itself can be used in this case. The counterfeits show spirals which are meagre, irregular, tight, or the wrong colour; they do not fill up the stem, or exactly swell out to fill up the knops; in the cotton-white there are defects resembling dropped threads in a piece of linen, or missed stitches in a piece of lace. I possess one excellently twisted air-spiral forgery, a simple cable, which might deceive if the plain glass around it forming the rest of the stem were not so thick and so distinct as to suggest that the spiral was made first and the plain glass placed around it afterwards; the old spirals, air, cotton-white or coloured, were twisted at the time of and in the actual making of the whole stem. Modern spiral stems are often writhen or ridged on the surface, too; which means that the twisting of the stem has been done with less than the old amount of skill. In short, the making of spiral stems is a lost art, not recovered even by the assiduous forgers, up to the present.
If a spiral revolves upwards from right to left—the right to the left of the person looking at it—reject it; this defect was a feature of the earlier forgeries, but the proper direction of the upward twist (from left to right) is now used in these fakes.
The old cut stems are more easily imitated: with these a test is the absence of all trace of a pontil-mark. In many old cut glasses the finger feels a distinct depression, usually circular, which shows where the old pontil-mark was cut away. In some forgeries, made by moulding, not by blowing, the pontil-mark is imitated, but so grossly that it ought not to deceive.