About DGL

If you are buying diamonds, gemstones, jewellery, fine watches or precious metal you may have concerns about the value, origin, quality and authenticity of your investment.  A DGL Certificate is a statement issued by one of our independent gemological laboratories which document the detailed characteristics of your investment. DGL  grading certificates are recognized for their accuracy and integrity, defining industry standards in evaluation and appraisal. The U.S. laboratory is based in Los Angeles, California and the Asia laboratory is based in Jakarta , Indonesia.

In addition to identification, grading, and authentication DGL provides independent appraisals in US dollars. A common reason to obtain a stone, jewellery or fine watch appraisal is to either have a realistic retail value or to have a retail replacement value for insurance coverage. Jewelry appraisals also allow families to divide their estate jewelry more fairly. DGL has offered certifications, appraisals and consultations for over 30 years.

We offer unbiased, legal, certified document appraisals based upon 30 years of experience as well as dealer price reports, trade publications, auction prices and contact with suppliers and dealers.

The Jakarta office usually completes the analysis on loose gemstones and diamonds immediately. Customers can wait in the office and leave with the completed report(s).  Certifications and appraisals by our California gemologists are for the trade only and not open to the public.

  About the Founder 

Dennis began on the corporate side of precious metals mining in 1979. From his base in the State of Nevada he went to Australia to work in field operations (1983) and then to precious metal and precious stone mining in Brazil (1984-1987). Dennis' interest in gemology began in the mid 80's where he received his graduate gemologist degree from IGB-Instituto Gemologico do Brasil. Now fluent in Portuguese and an expert in Brazilian gemstones (emeralds, aquamarine, imperial topaz, opals, et al.) Dennis moved onto diamonds. With his knowledge of the gemstone and diamond producing regions in Brazil he began his own diamond mining operation in 1988. The same year Dennis received his diamond grading diploma from GIA. With his knowledge of precious metals, colored gemstones and diamonds he began doing gemological certifications and appraisals for the jewellery trade and for VIP clientele from his base in the Los Angeles Jewelry District. 

On his many travels he found himself in the diamond producing region of Kalimantan.  Dennis became fascinated with the history and geology of the region and based himself in Jakarta (1996-1999). Back in Los Angeles from 2000 to 2012 he went beyond gemological research, certification and appraisal to become an expert in antique jewelry authentication and valuations. Mr. Dufau was founder and President of the Gemological Institute of America (GIA) Alumni Association of Indonesia. The labs closed temporaily from March 2020 to August 2021.

In 2019 Hollywood productions, declared an essential business; were one of the few industries allowed to open during the pandemic. At that time Dennis began Hollywoodstudioservices.com which now has the largest selection of original period jewelry rentals for Hollywood costume and prop departments.