SSEF Blue Diamond Tester™ available for semi conductive type IIb

SCHWEIZERISCHES GEMMOLOGISCHES INSTITUT
INSTITUT SUISSE DE GEMMOLOGIE
SSEF
SWISS GEMMOLOGICAL INSTITUTE
instruments
SCHWEIZERISCHES GEMMOLOGISCHES INSTITUT
INSTITUT SUISSE DE GEMMOLOGIE
SSEF
SWISS GEMMOLOGICAL INSTITUTE
instruments
along graphite coatings. Use a second technique to identify the mineral species (thermotester,
reflectometer, UV reaction etc.).
SSEF Blue Diamond Tester™ available
for semi conductive type IIb diamond identification
Why testing diamonds with the SSEF Blue Diamond Tester™?
In the course of the identification of high pressure/high temperature HPHT treated diamonds the trade
became sensitive to understand the characteristics of the different diamond types. Around the year 2000
it became common knowledge that some brown IIa diamonds could be de-colorised (i.e. GE POL,
Monarch™, Bellataire™). Later we were aware of the HPHT treatment of brown type Ia diamonds which
yields lemon green to yellow diamonds. Less well known is the fact that, among the treatable brown type II
diamonds, some became pink and blue. The brown colour can thus mask colourless, pink and blue
stones, the latter being of type IIb.
The application of the electrical conductivity tester allows an easy separation of boron containing
diamonds and diamonds with no semi conductive capacity.
Interesting News
The SSEF Blue Diamond Tester™ is a portable device to check the electrical conductivity of diamonds.
What are you testing when you use an SSEF Blue Diamond Tester™?
You are testing the electro conductivity by holding the sample between two metal probes.
Boron doped diamonds (type IIb) either natural or synthetic, are bluish, blue or bluish grey in their original
state. Natural type IIb diamonds may have received lattice crystal damage, leading to a brown secondary
colour which can mask the attractive primary colour. Similar to other type II diamonds, such lattice defects
can be restored by a HPHT treatment, resulting in a removal of the brown colour.
The SSEF Blue Diamond Tester™ does not indicate a HPHT treatment performed to a blue diamond.
We stronly recommend, however, to have identified a possible HPHT treatment on a blue diamond in a
specialised gemmological laboratory performing cryo- luminescence spectrometry (e.g. SSEF, Gübelin,
AGTA).
- Type Ia diamonds are containing nitrogen, and are considered insulators for electrical potential. This
type represents the majority of gem diamonds (Cape stones)
- Type Ib diamonds are containing nitrogen (Canary), and are considered insulators for electrical current.
- Type II diamonds are considered free of nitrogen at normal trace levels.
- Type IIa diamonds are insulators for electrical current.
- Type IIb diamonds contain traces of boron, and are semiconductors. Type IIb diamonds transmit
electrical current to some extent.
How to order the SSEF
Blue Diamond Tester™?
The instrument is produced by
SSEF. Orders are placed directly
to SSEF or to a intermediate.
The tool should be completed
with four 9 volt batteries which
are not delivered when the Tester
is shipped.
How to use the SSEF Blue Diamond Tester™?
1) The diamond has to be put table down on the sample disc (see picture above). With the metal tip
of the pencil-like pointer you touch the diamond's surface. Make sure you provide good contact.
2) IMPORTANT: When you touch the golden sample disc directly with the pointer, the potentiometer turns
as a reaction on the full voltage of the batteries. Under these conditions the needle can get adjusted to
100. This is also a battery test.
.
3) Ensure a good contact of the stone by using a large surface! Poor contact may result in a false
reading, i.e. no reaction. With the pointer you must gently press the stone down and against the metal
rim.
4) Two reactions are possible:
The needle of the potentiometer will not move when the pointer touches the stones surface. The stone is
an electrical insulator.
The needle will swing towards higher values when the pointer touches the stones surface. The diamond
is of type IIb and a semi conductor.
.
- WARNING: Not all semi conductive brilliant cut stones are type IIb diamonds! Synthetic moissanite
may react like type IIb diamond. Black diamond with graphitised fissures will also conduct electricity
For prices and further information, please contact SSEF:
SSEF diamond spotter and SSEF diamond illuminator
SSEF diamond spotter and SSEF diamond illuminator
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SSEF Swiss Gemmological Institute, Falknerstrasse 9, CH - 4001 Basel, Switzerland
tel: ++ 41 (0)61 262 06 40
fax: ++41 (0)61 262 06 41
website www.ssef.ch
email [email protected]
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