Looking Back At the Future

Chaim Even-Zohar writes about the lack of liquidity in the diamond industry, bankruptcies, lack of success in the development and financing of branded diamonds + other viewpoints @ http://www.idexonline.com/portal_FullEditorial.asp?TextSearch=&KeyMatch=0&id=26653

How To Identify Lechleitner Synthetic Hydrothermal Emerald

Lechleitner emerald-coated beryl (Emerita - first marketed in 1960 by Austrian Johann Lechleitner in 1960, Austria). Produced hydrothermally by growing a coating of synthetic emerald over an already faceted specimen of natural colorless or pale colored beryl.

Detection
- Crazed effect in overcoat layer with cracks intersecting at 90°.
- Generally poor polish (repolishing may cause bald patches); some small back facets left unpolished to enhance depth of color.
- Dark rim of overgrowth area (best seen when stone immersed methylene iodide).
- Overgrowth area may fluoresce (weak to moderate red (LW & SW).
- Depending on the type of beryl used for the core (e.g., pale pink beryl or aquamarine), S.G. and inclusions noted might be wrong for emerald.

Lechleitner sandwich
Composite of natural or synthetic colorless beryl with overgrowth of dark green synthetic emerald. The sandwich type was first produced in 1964. Seed plate is of natural or synthetic beryl upon which a plate of emerald is grown. This may be subsequently enlarged by growing on synthetic colorless beryl. Multiple sandwiches have also been produced.

Detection
-Magnification: typical hydrothermal inclusions (and physical constants)
- Structure is only exhibited when viewed from the side or when immersed in a suitable liquid.
- Nail-like growth tubes may be seen streaming away from the seed crystal.

Lechleitner types

- Type 1
Thin hydrothermal synthetic emerald skin grown on a faceted natural colorless beryl seed. The skin displays a characteristic checkerboard-like appearance of narrow cracks. Thickness of the overgrowth varies from one facet to another, resulting in obvious differences in the depth of color on different facets. Natural inclusions may be found in the seed.

- Type 2
Sandwich-like consisting of a thin slice of natural colorless beryl surrounded by hydrothermal synthetic emerald. The colorless seed generally is found at the girdle and runs parallel to the table. Inclusions are the same as in type 3 & 4.

- Type 3 & 4
Full hydrothermal synthetic, featuring nails-like, unidentified tiny black and red specks, straight color zoning, etc.

The stones are rare. They are found only in a few gemological schools and gem research laboratories for study purposes.

Jewelry Information Center Launches Vlogs

The Jewelry Information Center (JIC) has launched a series of video blogs (vlogs) on its website www.jic.org to reach out to manufacturing and retail members + educate consumers in a simple format.

Which Are The Famous Films About Gold?

- Goldfinger

- The Italian Job

- The Maltese Falcon

- The Lavender Hill Mob.

Tax Amnesty: Veni, Vidi, Vici

Chaim Even-Zohar writes about the concept of inventory revaluation introduced by the Diamond High Council (HRD) and the Belgian government + the accounting practices applied in the diamond sector between second world war and 1995 + other viewpoints @ http://www.idexonline.com/portal_FullEditorial.asp?TextSearch=&KeyMatch=0&id=26738

How Doctors Think

Most physicians already have in mind two or three possible diagnoses within minutes of meeting a patient. Jerome Groopman writes about the concept of cognitive dimension of clinical decision-making—the process by which doctors interpret their patients’ symptoms and weigh test results in order to arrive at a diagnosis and a plan of treatment @ http://www.newyorker.com/reporting/2007/01/29/070129fa_fact_groopman

It is interesting to analyze the similarity of clinical decision making by doctors with gem identification. The experts have a sweet way of describing the process. Gem identification is a logical process of deduction or alternatively of elimination. The gemologist performs a series of observations and tests upon a particular stone and with each test will eliminate some of the possible identities of that stone. Finally through step-by-step testing only one identity will fit the stone in question. This is the end point of the exercise, to identify an unknown material in terms of its mineralogical group, species and variety.

How To Identify Lechleitner Synthetic Ruby

The veteran Austrian crystal grower Johann Lechleitner is the genius behind the production of synthetic corundum in a variety of colors by the flux process. The experimentation began in 1983. As with Knischka, Lechleitner uses seeds as a focus for growth. His production can be divided into two types depending on the type of seed used.

- Type 1
Growth on Verneuil seeds. These are grown in a variety of colors (red, pink, orange, blue, yellow, green and colorless) with the color of the seed usually matching that of the overgrowth. Inclusions are characteristic of both the flux method of growth (reminiscent of Kashan and Chatham synthetics) and of the Verneuil seed (gas bubbles, curved striae and color banding). This is a characteristic and easily recognized assemblage of inclusions.

- Type 2
Growth on natural corundum seeds. This type of Lechleitner synthetic requires much closer attention. The synthetic overgrowth will adopt the crystal habit of the seed underneath and reproduce growth structures identical to the natural material (i.e. an overgrowth on a Thai ruby seed will produce a tabular crystal of identical habit to the natural crystal). Repeated twinning found in the seed will continue out into the overgrowth.

Inclusions in the seed portion can easily confuse the eye, especially if the identification is hasty. Features typical of flux-growth corundums should be seen in the overgrowth. The best method of detecting type 2 corundums would seem to be with immersion in high RI liquid, but even with this technique it may be difficult to see the boundary between the seed and the overgrowth (this should be present as a narrow colorless layer at the junction). Unfortunately, the growth process seems to use such high temperatures that the surface of the seed may be actively dissolved by the flux, making the junction between seed and overgrowth harder to detect.

The cutting process may also remove much of the overgrowth, in which case the inclusions within the seed would be more noticeable than the flux inclusions left in the vestiges of the seed. One consequence of using a natural seed will be the difference in fluorescence between the two 'components' of the stone. Under longwave ultraviolet light the natural seed will glow a much weaker red than the overgrowth, which will fluoresce bright red.

The stones are rare. You may find the specimens only at a few gemological schools, gem research laboratories and among private collectors.

China's Gemstone Market Booms

Chen Nan Yang writes about the total size of the jewelry, colored stones including jade market @ http://www.colored-stone.com/stories/mar07/china.cfm