Diploma in Diamond Grading - Rough and Polish DiamondsGemmological Institute of India
Frequent Asked Questions
Minimum eligibility is SSC. However, gemmology is a professional course. It has more of practical application rather than theoretical. If one has working knowledge of English, it is sufficient to take up the courses.
As India is the leader in the exports of diamonds in the world market it is essential to know the quality diamonds to cater to the requirement of global market. To grade the diamonds for its clarity, colour and cut as per the international standard is what the GII is established for.
Polished diamond grading is taught by highly qualified diamond graders Ms. Sucheta Chudawala and Dharmesh Pachchigar.
Rough assortment is the most complicated aspect of the diamond industry. Rough diamonds are assorted taking into account or calculating the resultant shape, clarity colour of the finished diamond. GII developed a course by which students are taught as to how to judge the rough diamonds for its qualitative aspects such as clarity, colour, yield and determine the shape. Rough diamond assortment teaches the vital information for assessing the colour and clarity of the final cut and polished diamond. GII imparts intensive training to judge the yield of a rough diamond.
Mr. Zubin Lakdawalla is incharge of the rough diamonds department. He is a highly qualified and experienced gemmologist and diamond grader in India.
1. CHEMICAL COMPOSITION :
Different forms of carbon (graphite, amorphous, diamond).
2. GEOLOGICAL OCCURRENCES AND THEIR HISTORY : Gem and industrial diamond, kimberlite (mines); Alluvial deposits (river beds), Marine deposits (beaches, sea-bed); Meteoric diamonds; Localities like Australia; Borneo; Brazil; India; Sierra Leon; Russia; South Africa; South West Africa, Zaire, Canada etc.
3. EXTRACTION OF DIAMONDS : Crushing, Washing and Screening, Heavy media separator; Grease table, Grease belt, X-ray separation.
4. OPERATION OF THE MARKET : De-Beers consolidated Mines; Diamond Trading Company (D.T.C.); Sights supplied by D.T.C.; Diamond Bourses; Clubs; Operation of the National and International markets. Sources of Rough diamonds: HDC, MMTC, NMDC, Local-resellers, DTC, Open market.
5. CRYSTALLINE FORMS OF DIAMONDS AND PHYSICAL PROPERTIES: Crystallography, Nature of crystals; Systems of crystallography; Cubic system; Forms; Twins, Parallel growth; Irregular forms; Growth features, Fracture; Cleavage; Hardness (Moh's Scale); Specific gravity (Heavy liquids and Hydrostatic method); Electrical conductivity. Thermal conductivity; Graphitization.
6. OPTICAL PROPERTIES : Single; double and anamolous double refraction, Refractive index; Strain patterns; Dispersion; Absorption spectra; Transparency to Ultra-violet and x-rays; Reflectivity; Luminiscence.
7. SORTING OF ROUGH DIAMONDS : Sorting by Size; Shapes; Colour; Purity.
8. HISTORY OF CUTS : The modern brilliant cut; Variation of the brilliant cut; Principles of diamond cutting; Lustre, brilliance, fire, ideal cuts and proportions; Variation from the ideal cut.
9. MANUFACTURING OF DIAMONDS : Grains; Sawing; Cleaving; Bruting; Grinding; Polishing; 4,3,2, point stones; Acidizing; Ultrasonic cleaning.
10. COLOUR GRADING OF POLISHED STONES : Lighting standards and magnification; Comparison stones. Colour grading systems (G.I.A.; HRD; Indian, C.I.B.J.O.)
11. CLARITY GRADING OF POLISHED STONES : Magnification; Lighting; International grading scales; (G.I.A.; HRD; Indian; C.I.B.J.O.); Criteria for grading; Internal blemishes; External defects.
12. GRADING FOR CUT : Spread stones; Lumpy and Fish-eye stones, Proportion scope and proportion analyzing, Carat system; weighing scales; Estimating weight of mounted stones (gauges); Sieves and sieve sizes. Estimating: Table percentage, Pavilion depth, Crown angle, Pavilion angle and Girdle thickness.
13. SYNTHETIC DIAMOND : Synthesis; Artificial colouration; Identification of treated diamond.
14. IDENTIFICATION OF DIAMOND : With 10x only and with Instruments; Types of Diamond and Classification.
15. DIAMOND SIMULANTS : Gadolinium Gallium Garnet (GGG); Yttrium Aluminium Garnet (YAG); Strontium Titanate; Synthetic Rutile; Synthetic Cubic Zirconia; Synthetic moissanite; Spinel, Sapphire; Zircon; Topaz; Quartz; Paste, Doublets.
16. PRACTICALS : Clarity Grading, Yield estimation and planning of Rough Diamonds, Clarity, Cut and Colour grading of polished diamonds.