Separation of Blue Spinel Colored by Cobalt With

Gems & Gemological Institute of Pakistan(GGIP)-Peshawar.

1

9/23/12 Gems & Gemological Institute of Pakistan-Peshawar. 2

Separa&on of Natural Blue Spinel Colored by Cobalt from imita&on/synthe&c gemstones with the help of color filters/

Ultraviolet Lamp OR

The effect of Blue stones colored by cobalt in Colored filters and in UV (Long wave/short wave)

Presented to my best Japanese friend Akira Kono

CEO of SERAPH & Co. Izumi, Osaka, Japan. Reported and prepared by Hamid Usman KhaIak (HUK)-‐AG Gemologist

Gems and Gemological Ins&tute of Pakistan (GGIP)-‐Peshawar.


Separa&on of Natural Blue Spinel Colored by Cobalt from imita&on/synthe&c gemstones with the help of color filters/ Ultraviolet Lamp

OR The effect of Blue stones colored by cobalt in Colored filters and in UV (Long wave/short wave)

}  Introduc&on }  Blue spinel colored by cobalt is reported in Vietnams, Hunza valley Pakistan and in Sri lanka.

}  Cobalt is a lustrous grayish silvery metal. It is very hard and can take very good polish.

}  Cobalt is also ferromagne&c and therefore is capable of being magne&zed.

}  Cobalt is a transi&on element and when it found in minerals or in gemstone in traces it produce two type of colors

}  1.Blue 2. Pink. }  Blue mineral and gemstone due to Cobalt are Lusakite and Blue spinel.

}  Pink minerals due to cobalt are Erythrite, roselite, spherocobal&te.


Separa&on of Natural Blue Spinel Colored by Cobalt from imita&on/synthe&c gemstones with the help of color filters/ Ultraviolet Lamp

OR The effect of Blue stones colored by cobalt in Colored filters and in UV (Long wave/short wave)

Aim of the introduc&on of new test in Gemology: The objec&ves of the introduc&on of this test are •  to iden&fy the gemstones through a sample instrument

(advanced gemological instruments are very expensive and their prices may be equivalent to GGIP fund).

•  To introduced quick iden&fica&ons methods to save the precious &me (easily separate blue spinel from blue stone lot)

•  Promote the using of sample gemology tes&ng tools which are easily available and affordable.

•  To promote an easy gemstones iden&fica&on methods which can handle easily a common trade people.


Test Details

•  Details of the conduct test : For carry out this test I selected 10 cut and polished blue stones( glass and spinel) of different tone and saturaMon. Due to unavailability of cut blue spinel I selected one number of blue spinel specimen , locality Hunza , Pakistan.


Separa&on of Natural Blue Spinel Colored by Cobalt from imita&on/synthe&c gemstones with the help of color filters.

Different tone and saturation synthetic spinel colored by cobalt.



Different tone and saturation Glass(Paste) colored by cobalt.



Natural Blue spinel colored by cobalt specimen . Many spinel crystals can be seen embedded in the calcite .



The selected gemstones for testing From left to right, first five are blue glass colored by cobalt then in middle one is

Natural spinel colored by cobalt specimen and other five stones are Synthetic spinel colored by cobalt.


Tools need for this test

1.  To carried out this test we needs

two types of filters and strong over head light (tungsten light is preferable) and white back ground.

2.  Ultraviolet lamp with capability of Long waves(LW) and short waves (SW), Black background.

• 


SeparaMon of Natural Blue Spinel Colored by Cobalt from imitaMon/syntheMc gemstones with the help of color filters

•  Filters which we needs: The filters are divided into two category

1. OpMonal filters 2. Compulsory filter. 1. OpMonal filters : op&onal filters means that availability of any one filter is enough for this test.

2. Compulsory filter. Compulsory filters means that without availability of this filter we can not do this test.



•  1. OpMonal filters •  In op&onal filters we are required any one of the following filters 1.Chelsea filter 2.Aqua filter 3. SyntheMc Emerald filter(The described three filters gives the same

result) •  2. Compulsory filter. •  For this test the Synthe&c Emerald support filter is considered a compulsory filter.



Optional filters and Compulsory filter. Chelsea , Aqua and synthetic Emerald filter are optional filters and Synthetic support Emerald filter is Compulsory filter.



•  TesMng Procedure: placed the stones on white background under the strong over head light and see through the filters

•  Effect in opMonal filters: All the stones turn to red.

•  Effect in compulsory filter: on viewing through the Synthe&c Emerald support filter I obtained the following result


Separa&on of Natural Blue Spinel Colored by Cobalt from imita&on/synthe&c gemstones with the help of color filters

•  All the glass of different tone and saturaMon do not changes its color

•  Natural blue spinel colored by cobalt turn into strong red.

•  SyntheMc spinel colored by cobalt stone turn its color into Pale color and on stone turn it color in very light reddish shade.


op&onal filters

1. Effect in Chelsea Color Filter (CCF)

In Chelsea filter all the stones turns to red. optional filters

Separation of Natural Blue Spinel Colored by Cobalt from imitation/synthetic gemstones with the help of color filters


op&onal filters

2. Effect in Aqua Color Filter

optional filters

In Aqua filter all the stones turns to red. Same result as Chelsea filter.



op&onal filters

2. Effect in Synthe&c Emerald color filter.

In Synthetic Emerald filter all the stones turns to red. Same result as Chelsea filter and Aqua filter

optional filters



Compulsory filter

Effect in Synthe&c Support Emerald Filter.

Compulsory filter 1. Glass do not changes its color 2. Natural blue spinel colored by cobalt turn into strong red. 3. Synthetic spinel color by cobalt turn its color into Pale color and one stone turn it color into very light red shade or Pastel red color. Separation of Natural Blue Spinel Colored by Cobalt from imitation/synthetic gemstones with the help of color

filters



From left to right Rectangular cut syn.spinel Turn it color into very light red and the other two Syn. Spinel stones looks pale color.



Same stones but with different background From left to right Rectangular cut syn.spinel

Turn it color into very light red and the other two Syn. Spinel stones looks pale color.



Dark color Syn. Spinel in Compulsory filter



Natural Spinel specimen in Syn. Support Emerald Filter In syn. support Emerald Filter Natural spinel turns its color Into strong Red.


SeparaMon of Natural Blue Spinel Colored by Cobalt from imitaMon/syntheMc gemstones with the help of color filters.

Summary of the effect of Blue stones colored by cobalt in Colored filters.

S# Gems Effect in OpMonal filters

(Chelsea, Aqua, SyntheMc Emerald

filter)

Effect in Compulsory filter (syntheMc Emerald support filter)

comments

Nat. Blue Spinel Red Red In all the men&oned look red

SyntheMc Blue Spinel Red Pale to Very light red

Some stones turns to pale color and one stone turn to very light red &nt color.

Blue Glass Red Inert


The effect of Blue stones colored by cobalt in Colored filters

and in UV (Long wave/short wave)

•  TesMng Procedure: placed the stones on black background and note stone's reac&on in the type of radia&on used -‐ whether long waves or short waves.

•  Effect in Long waves: In long waves the blue glass show no change (inert), Natural spinel turn to red and syn. Spinel also turn to red.

•  Effect in Short waves. In short waves the blue glass turns to chalky, Natural spinel show no change (Inert)and syn. Spinel turn to chalky.


The effect of Blue stones colored by cobalt in Colored filters and in UV (Long wave/short wave)

Summary of the effect of Blue stones colored by cobalt in Long waves/Short waves

S# Gems Effect in LW Effect in SW Comments

1 Nat. Blue Spinel Red Inert

2 SyntheMc Blue Spinel Red Chalky Light color stones strong chalky in SW as compared to intense color stones

3 Blue Glass Inert Two type effect 1.  Majority Chalky 2.  Yellowish color

It is observed that the glass which show yellowish color in SW have magne&c property., weak to moderate. But blue glass show chalky effect in SW have no magne&c property.


Effect in Long waves/Short waves

In Short waves blue glass colored by cobalt turns into two types 1.  Chalky (mostly) just like Syn.spinel 2.  Turn into yellow color and this type glass show magnetic property weak to

moderate.



In Long waves syn. Spinel colored by cobalt turns to Red In short waves syn. Spinel colored by

Cobalt turn into Chalky Note: The syn. Spinel which body color is Light blue shows strong chalky effect as Compared to dark color syn. Spinel.



Natural spinel colored by in Long waves In Long waves Natural spinel colored by cobalt turns into strong red But in short waves it show inter.


Other SupporMng Tests

Following are the suppor&ng tests 1. Spectrum 2. Refrac&ve index 3.Magne&c Effect


1.Spectrum

Synthetic spinel colored by cobalt: Three broad bands centered at 540, 580, (Broadest) and 635: (Thin Thick Thin) Blue Glass colored by cobalt: Three broad bands centered at 535, 590 (Narrowest) and 655. (Thick Thin Thick) Natural Blue spinel colored by cobalt spectrum


2.Refrac&ve Index

S# Gems RefracMve Index (RI)

comments

1 Natural Blue Spinel colored by cobalt

1.718 Mostly

2 SyntheMc Blue Spinel colored by cobalt

1.728 or 1.730

3 Blue Glass colored by cobalt

1.50 or 1.51 or 1.52

Mostly.


3.Magne&c Effect

S# Gems MagneMc effect comments

1 Natural Blue Spinel colored by cobalt

yes

2 SyntheMc Blue Spinel colored by cobalt

None I checked many specimen of synthe&c spinel of different tone but found no magne&c effect.

3 Blue Glass colored by cobalt

Some blue glass have weak to moderate

magneMc effect and some blue glass show no

magneMc effect .

Note: It is observed that the blue glass which show yellowish color in SW have magne&c property., weak to moderate. But blue glass show chalky effect in SW have no magne&c property.


Acknowledgement ,References and suggested reading

1.www.MineralsUK.com 2. hIp://www.minsocam.org/msa/collectors_corner/arc/color.htm 3.hIp://www.gemlab.jkharris.co.uk/Synthe&c%20blue%20Spinel%20and%20Co.Glass.html

4.hIp://gemologyproject.com/wiki/index.php?&tle=Spinel

Note: Everyone can use this presenta&on for educa&onal purpose without my

permission. Gems & Gemological InsMtute of Pakistan (GGIP)-‐Peshawar slogan is “Gemology for everyone”.

because gemology is not the property of Mineralogist, Geologist, Engineer, IT expert, or any other profession or trade which directly or indirectly related to it.

Hamid Usman KhaIak (HUK)-‐AG Gemologist

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Separation of Blue Spinel Colored by Cobalt With