BLUE COBALT SPINEL 3.04 ct, GFCO, MELIKIAN
GEMOLOGICAL REPORT № 133
Gemologist Olga Melikian | WA: https://wa.me/79990437349 24/01/2026
Telegram: @olgamelikianofficial | https://melikianjewelry.com
Weight: ……………………………..………………………….. 3.04 ct
Measurements: ……………….………..……… 9.18x7.38x5.28 mm
Сut: ……………………………………………..………….…. cushion
Color / Color saturation: ………. vivid blue | strong color saturation
Clarity: …………………….………….………………….… loop clean
IDENTIFICATION: ………………………………… Natural SPINEL
TRADE NAME: …………………………… BLUE COBALT SPINEL
Geographic Origin: ………………………………………… Tanzania
Treatment: ……………………..………. No indication of treatment
10x glass: ………..…. clarity loop clean, quality of the cut excellent
Refractive Index: ……………………………………………….… 1.716
Polariscope: ………………………………..…………..…….. isotropic
Dichroscope: ………………………………….……… no pleochroism
UV fluorescence: ………….………………………… no fluorescence
Chelsea Filter: …………………………….……………………….…….
Color change | Alexandrite effect (daylight | artificial light): ……. no
Microscope: No indication of treatment (fillers, heating). There are gas-liquid inclusions, no mineral inclusions were found.
Special properties:
Opalescence | adularescence | iridescence ………………………No
Cats eye effect…………………………………………….……….…No
Asterism……………………………………….………………………No
Gemologist Olga Melikian | WA: https://wa.me/79990437349 24/01/2026
Telegram: @olgamelikianofficial | https://melikianjewelry.com
Weight: ……………………………..………………………….. 3.04 ct
Measurements: ……………….………..……… 9.18x7.38x5.28 mm
Сut: ……………………………………………..………….…. cushion
Color / Color saturation: ………. vivid blue | strong color saturation
Clarity: …………………….………….………………….… loop clean
IDENTIFICATION: ………………………………… Natural SPINEL
TRADE NAME: …………………………… BLUE COBALT SPINEL
Geographic Origin: ………………………………………… Tanzania
Treatment: ……………………..………. No indication of treatment
10x glass: ………..…. clarity loop clean, quality of the cut excellent
Refractive Index: ……………………………………………….… 1.716
Polariscope: ………………………………..…………..…….. isotropic
Dichroscope: ………………………………….……… no pleochroism
UV fluorescence: ………….………………………… no fluorescence
Chelsea Filter: …………………………….……………………….…….
Color change | Alexandrite effect (daylight | artificial light): ……. no
Microscope: No indication of treatment (fillers, heating). There are gas-liquid inclusions, no mineral inclusions were found.
Special properties:
Opalescence | adularescence | iridescence ………………………No
Cats eye effect…………………………………………….……….…No
Asterism……………………………………….………………………No
BLUE COBALT SPINEL 3.04 ct, GFCO, MELIKIAN
DETAILED GEMOLOGICAL COMMENT
To accurately determine the mining region, the gem report should be supplemented with Raman microscope study, obtaining the spectrum of this Blue cobalt spinel, and comparing it with the base spectrum of Blue cobalt spinel from Tanzania.
Considering the characteristics of this Blue cobalt spinel:
Weight: ……………………………..……………………….….. 3.04 ct
Сut: ………………………………………………….….……… cushion
Color / Color saturation: ….…… vivid blue | strong color saturation
Clarity: …………………….………………………………… loop clean
Geographic Origin: …………………………….…………… Tanzania
Treatment: …………………….….……. No indication of treatment
Recommended market value corridor (retail price) of Blue cobalt spinel from Tanzania weighing from 3 carat, loop clean clarity, and vivid blue color with strong color saturation as of 17.05.2025:
1800-2200 $ per 1 ct
Note: the recommended market value corridor in indicated on this date. The price may change over time. The value corridor is an opportunity for the buyer/ seller to get an objective assessment of the value of this stone. With the receipt of new gemological research data, the cost corridor may be revised.
To accurately determine the mining region, the gem report should be supplemented with Raman microscope study, obtaining the spectrum of this Blue cobalt spinel, and comparing it with the base spectrum of Blue cobalt spinel from Tanzania.
Considering the characteristics of this Blue cobalt spinel:
Weight: ……………………………..……………………….….. 3.04 ct
Сut: ………………………………………………….….……… cushion
Color / Color saturation: ….…… vivid blue | strong color saturation
Clarity: …………………….………………………………… loop clean
Geographic Origin: …………………………….…………… Tanzania
Treatment: …………………….….……. No indication of treatment
Recommended market value corridor (retail price) of Blue cobalt spinel from Tanzania weighing from 3 carat, loop clean clarity, and vivid blue color with strong color saturation as of 17.05.2025:
1800-2200 $ per 1 ct
Note: the recommended market value corridor in indicated on this date. The price may change over time. The value corridor is an opportunity for the buyer/ seller to get an objective assessment of the value of this stone. With the receipt of new gemological research data, the cost corridor may be revised.