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Essentials on coloured gemstones

This course teaches you to identify the different types of stones; including the colour shades, size, proportions, optical phenomena, and other factors that influence the value of a gemstone.

Colored stones, sale, purchase and quality of the cut

This course requires the basic gemmology course or another degree in gemmology as a prerequisite.

The content of this course focuses on the most important factors determining the value of a coloured stone. The student will mainly work with commercial stones that are found on the market.

Topics covered and tools available during the course

  • Analysis of the main gemstones by species and varieties.
  • The factors determining the price of a colored stone:  size, color, carat, purity, provenance, etc.
  • The factors determining the quality of a cut stone.
  • Local and overseas buying and selling techniques.
  • The journey of precious stones, from the source to the sale.
  • The price of precious stones at their source.
  • Instruments available:  10x loupe, tweezers, vertical/horizontal microscope, immersion liquid,  dichroscope, refractometer, polariscope,  conoscope, spectroscope, optical fiber, ultra violet, hydrostatic balance and caliper.
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Work equipment

  • Support: the essentials on colored stones.
  • Optional Book: Gemstones Quality and Value vol. 1 (Yasukazu Suwa).
  • Optional Book: Gemstones Quality and Value vol. 2 (Yasukazu Suwa).

The courses are arranged according to your availability

The dates & times of the courses are to be agreed between the student and the teacher. The schedules are Monday to Friday from 9am to 12pm and from 2pm to 5pm, and Saturday from 9am to 12pm. If you are not available during the day, a range can be agreed in the evening from 6pm to 9pm (except Saturday and Sunday).

The total duration of the course is 12 hours, four lessons of three hours.

Price of the course, CHF 800.

This course is taught by David Arredondo, teacher responsible for gemmology and precious metals courses.

A certificate is delivered following an exam. The test lasts three hours, consisting of a theoretical and practical part.