New Artificially Asteriated Gemstones Carlsbad, May, 2011

New Artificially Asteriated Gemstones
Carlsbad, May, 2011
Martin P. Steinbach
STEINBACH, Gems With A Star, Idar-Oberstein, Germany
Gems with asterism, the star effect, have a continually growing congregation of fans with
dealers, collectors and jewellery designers.
The minute, oriented inclusions of these star gems are able to create the 4, 6, 8, 12, 18 or even
24 rays of a star. In addition to the well known stones with four-rayed and six-rayed stars, this
presentation mentions a few new and rare precious gems and varieties.
Synthetic star corundum is known since about 1947 and the widely spread diffusion treated
blue star sapphires appeared on the market in the mid 1980s (Nassau, 1981).
It cannot be warned enough about these diffusion treated stones. They are frequently offered
as genuine star stones. According to CIBJO, the treatment of these stones has to be disclosed.
Unfortunately, this is not always done, especially when the stones are offered on the web. In
these stones the star and the color are diffused. The stars of the stones are too sharp and the
blue color in all hues is distributed too intense and too evenly.
Artificially etched crystal faces or scratched metal plates to create asterism were already
mentioned in the first half of the 19th century.
As new effect stones, gems with a scratched star appeared about 10 years ago on the market.
This scratched star is made artificially, probably by hand by “artists” in Sri Lanka. The
scratched stones mentioned in the international literature include garnet, chrysoberyl, rutile,
sinhalite, cassiterite, samarskite (scheelite?), tourmaline (schorl) and sphalerite.
In this presentation, the newly described and gemologically examined gems with a scratched
star are pyrite, iolite, green garnet, diopside, green tourmaline and sapphire (Fig.1 & 2).
Fig.1 Scratched star iolite, 4,57 cts
Fig.2 Scratched star pyrite, 28.01 cts
As an addition, gems with natural 4-, 6-, 8- and 12-rayed stars (Fig.3) are mentioned here, as
well as a twin star (Fig.4) and doublets to possibly imitate iolite and star tourmaline. Tests to
identify the scratched gems are also shown in this presentation.
Fig.3 Natural star iolite, 7.02 cts
Fig. 4 Twin star sapphire, 5.34 cts
How Are Scratched Star Stones Distinguished from Natural Star Stones?
The identification of this new manipulation is still relatively easy. The key – as often in
gemology – is to know that such manipulations exist and accordingly to scrutinize stones that
look odd.
The following factors should be taken into account:
- Unnatural look of the stars
- Absence of oriented, acicular inclusions in the stone
- Presence of oriented scratches on the surface of the cabochon
- Incomplete, crooked or asymmetrical rays of the stars
- So-called „satellite rays“ on the stone
- Extra-rays that are incompatible with the symmetry of the gemstone
- Gemstones with natural inclusions show stars that are most distinct when the camera is
focused above the domed surface of the cabochon. This finding is especially useful for
opaque and very dark stars where the inclusions causing the stars are very difficult to
perceive.
Conclusion
Approximately 40 different star stones are known, plus various trapiche varieties. The
scratched star stones, however, that are described here will stay collector stones or curiosities.
What is left is the exciting question whether some day a true star tourmaline or star sinhalite
will turn up.
References for Further Reading:
Dana, Edward S. and Ford, William E. (1932) A textbook of Mineralogy, 4. Edition, Chapter
Physical Mineralogy, New York, John Wiley & Sons Inc. p. 274-5
Gübelin, E.J. und Koivula, J.I. (1986) Bildatlas der Einschlüsse in Edelsteinen, ABC Verlag,
Zürich, p. 269
Hainschwang, T., Notari, F. and Anckar, B. (2007) Trapiche Tourmaline from Zambia, Gems
& Gemology, 43(1), pp. 36-46
Harding, R.R. (2002) A note on two star stones, J. Gemmol., 28, 4, pp. 231-234
Hyrsl, J. and Steinbach, M.P. (2009) Pseudo-chatoyancy and pseudo-asterism in sphalerite
from Spain, Gems & Gemology, 45(4), pp. 303-4
Maier, W. (1943.) Experimenteller Asterismus. Neues Jahrbuch für Mineralogie, Geologie
und Paläontologie, 78(3), pp. 283-380
McClure, S.F, and Koivula J.I. (2001) A new method for imitating asterism. Gems &
Gemology, 37(2), pp.124-8
Nassau, K. (1981) Heat treating ruby and sapphire – Technical aspects. Gems & Gemology,
Vol. 17, No. 3, pp. 121-131
Schmetzer, K. and Steinbach, M.P. (2001) Gemmologie aktuell – Künstlicher Asterismus,
Goldschmiedezeitung, 12/01, Stuttgart, p. 85
Schmetzer, K. and Glas, M. (2002) Another identification criterion for imitation asterism
produced by surface scratching, Gems & Gemology, 38, (2), p.185
Schmetzer, K. und Steinbach, M.P. (2002) Fake asterism – two examples. J. Gemmol., 28(1),
pp. 41-42
Schmetzer, K. (2002) Production of fake asterism, J.Gemmol., 28(2), pp. 109-110
Schmetzer, K. and Glas, M. (2003) Falsche „Sternsteine“; Manipulationen an Edelsteinen zur
Erzeugung oder Intensivierung von Asterismus, Lapis Magazin, Jg.28, Nr.1, pp.22-24 37-41
Steinbach, M.P. (2009) DVD „Sternedelsteine/Gems with a star“, Idar-Oberstein, Eigenverlag
Authors adress:
Martin P. Steinbach, AG, FGG, Tiefensteiner Str. 281b, D-55743 Idar-Oberstein, Germany.
Phone: 0049-6781-509942, mob. 0049-172-6856042, e-mail: [email protected],
www.star-sapphires.com.
All Photos © Martin P. Steinbach.