San Diego Gemological Laboratory

San Diego, California, United States of America

Avg. Rating Rating star5.0 (5 reviews)

Jewelry Appraiser's office
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About this Appraiser

San Diego Gemological Laboratory (SDGL) offers you a personalized experience that serves your specific jewelry appraisal need and can go further to satisfy your interest and curiosity about your unique jewelry item(s).

While working on your appraisal SDGL can help you discover more than just value. Your jewelry is not just a diamond or a gem. It reflects your life experiences or possibly those of past family members. Jewelry can reflect historical periods and contain clues to it′s past through cutting styles, quality of workmanship, design periods and even evidence of how an item was cherished or modified.

San Diego Gemological Laboratory subleases space for a fully independent office inside Leo Hamel Co., San Diego′s premier fine jewelry store, providing a secure, private, and intimate setting for your appraisal appointment. During your appointment Thom Underwood, GG FGA ASA CSM, San Diego′s only Master Gemologist Appraiser (ASA), will give you his undivided attention as he guides you through the appraisal process; identifying, describing, photographing and valuing your jewelry items, exploring the quality characteristics as well as possible provenance.

An appraisal can be more than just a report. It documents jewelry that is part of your history and your story. Whether your need is for confirmation of a purchase, consultation, insurance, estate or trust, SDGL is qualified to provide independent valuation services. SDGL is a fully equipped Certified Gem Lab (AGA) with nearly 40 years serving the San Diego area. Give SDGL a call today to schedule your appointment by using the contact links at the top of this page.


The Business

  • Private Practice & Trade Appraiser
  • Business mix: 100% appraisal
  • Principal + 0 staff Appraisers
  • Tues - Fri: 10am to 4pm
  • At Appraiser's office


  • Per-item and time-based fees
  • All major cards accepted
  • Full appraisal reports start at $135


Tap to Reveal

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  • GG, FGA
  • MGA


  • Gem-A, SGA, AGA


  • AGA - Antonio C. Bonanno Award

Curriculum Vitae


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While you wait jewelry appraisal


San Diego Gemological Laboratory
1851 San Diego Avenue
CA 92110

  • Accessible
  • Free, on-site
  • Visitors by appointment only
  • View large map


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Reviews (5)
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All reviews have been verified. The Jewelry Appraiser has confirmed the validity of the report details provided by the Reviewer but did not see the Reviewers rating or review text during the validation process. This produces unbiased, reliable and genuine reviews.


avatarElizabeth. Chula Vista

Review starsAug 2017

Knowledgeable, Professional & Master of His Subject

As a new resident of San Diego, I had need of a jewelry appraiser for insurance purposes. I found Thom at San Diego Gem Lab. I spoke to him and scheduled an appointment. He was very clear about what a jewelry appraisal for insurance purposes would entail and the cost per item appraised. His fees are quite reasonable. He answered all of my questions and I scheduled an appointment. Once I got there and had more time to talk to him about the jewelry I brought and the process, I was more impressed with his professionalism and his knowledge. He exceeded my expectations in every way. The report is comprehensive, easy to understand and just what I needed. I wouldn’t go to anyone else now that I have found him.

avatarSuburbanite. San Diego

Review starsApr 2017

Extreme Professionalism & Expertise

We had the pleasure of meeting with and having Thom Underwood determine the current value of several pieces of jewelry for insurance purposes. We could not have been more pleased. He exhibited a thorough and complete mastery of the appraisal process for each item we presented. Thom provided a detailed explanation of his methods and how he arrived at his conclusions. Clearly a leader in his field.

avatarWilliam Fitzgerald. San Diego

Review starsMar 2017

Excellent Service

Thom is friendly, professional, responsive, knowledgeable and detailed. I don't know how, but he made the process of appraising jewelry interesting and educational for me as I watched him work and he answered my questions. I found Thom via a google search and he was the only person who responded to me, and that was on a weekend! He worked around my busy schedule to set up an appointment for an insurance appraisal and I walked away with all of the documentation I needed. I wouldn't see anyone else in San Diego.

avatarKim S. San Diego

Review starsDec 2016

Excellent Professional

Thom appraised three rings for me. One was made by an artist and particularly challenging to value. He took the steps to learn the details to provide a fair evaluation. I had a lot of questions to the why/what of his evaluations and he answered every question, pulling out books to show me things.
I highly recommend him as I believe him to be very good at his craft, honest and is priced very reasonably.

avatarMr TaxMonkey. San Diego

Review starsJul 2016

Very professional

Thom handled the appraisal of my Father's jewelry for estate. It was completed thoroughly and professionally. He is very qualified and also personable, it was a pleasure to have met him.
I left with a sense of satisfaction and confidence in the appraisal. I highly recommend him not only for his skills and knowledge, but also for his interpersonal skills.