Our accredited gemologists

Our three experts and accredited gemologists will help and support every client with accuracy and professionalism.

Gemological analysis is a procedure based on the examination of gemstones, with the purpose of establishing their nature, their qualitative and quantitative features and the potential presence of artificial treatments meant to enhance the colour and/or the clarity.
One of the most important aspects that adds value to our activity is precisely our competence in the selection of gemstones, guaranteed by the dedicated and unvaried presence of our experts. This allows us to evaluate with proficiency diamonds and coloured inherited gemstones, before purchasing them either from privates or importers, in order to be a top-quality benchmark not only in Bologna, but also in Italy and abroad.s

Rapnet: an assurance at your disposal

Since 1926 Gioielleria Guidetti is a member of the Rapnet association, which is the largest and most reliable marketplace for sourcing and selling diamonds and jewelry.

The Rapaport catalog, which is published every week, indicates the quotation of diamonds according to dimensions, colour and clarity. This report is not accessible to everybody, but only to the expert members of the Rapnet association.

The Rapaport catalog is the only diamond assessment chart which is reliable, therefore for those who intend to invest on diamonds it is crucial to always consult experts in this field.

Since 1926 Gioielleria Guidetti has provided valuable advice in order to get the most out of your investment or to ensure the best buying conditions for second-hand diamonds, with the utmost privacy and fair market valuations.

Discover our readily available diamonds

find out

Discover our diamonds on request

find out

Our experts

Mario Guidetti, Riccardo Stefani and Anna Avantaggiato are three accredited gemologists who daily help and support our clients with reliability and professionalism.

Mario Guidetti
| associate

  • 1983 | Working in the shop as an associate and an employee
  • 1991 | Diamond Course Certificate at IGI, Milan
  • 1991 | Gemology Course Certificate at IGI, Milan
  • 1996 | Pearl Course Certificate at European Institute for Pearl Promotion
  • 1999 | Certificate of Specialization in Gemology at ENFAP, Emilia-Romagna
  • 2000 | Enrollment in the Register of Experts and C.C.I.A.A.
  • 2003 | Gemstones and Jewelry Valuation and Assessment at CISGEM, Milan
  • 2013 | Fancy Diamonds Workshop at HRD, Antwerp

Riccardo Stefani
| associate

  • 2014 | Master’s degree in management engineering
  • 2016 | Certified diamond grader (HRD, Antwerp)
  • 2017 | Coloured gemstones analyst (IGI, Milan)
  • 2017 | Pearl analysis and classification (IGI, Milan)

Anna Avantaggiato
| employee

  • University course in Geological Sciences
  • 2006 | Gemologist Certificate at IGI, Milan:
    Certificate of Gemological Analysis on Coloured Gemstones
    Certificate of Element Analysis and Classification Expert
    Diamond quality
    Certificate of Attendance to the Pearl Course
  • 2008 | Specialization Certificate – Title of Manufacturing Expert, Precious Stones Cutter and Setter at “Ghirardi” Goldsmith Professional School, Turin.
  • 2015| Rhinoceros 5 basic course in jewelry design.