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.