Mark Tanzi – Master Jeweler, Graduate Gemologist & Certified Gemologist
Mark Tanzi is a Master Jeweler, a Graduate Gemologist with Honors from the Gemological Institute of America (GIA), and a Certified Gemologist through the American Gem Society (AGS). With nearly half a century of experience buying, selling, evaluating, and working with luxury jewelry, diamonds, colored gemstones, gold, and precious metals, Mark brings an unusually broad combination of formal gemological education, hands-on jewelry knowledge, and real-world market experience to Pro Diamond Buyers.
His career has included buying and selling luxury jewelry and precious metals throughout major metropolitan markets across the United States, as well as extensive international gemstone-buying experience in Thailand. This combination of education, craftsmanship, market knowledge, and decades of practical experience allows Mark to evaluate valuable items from multiple perspectives rather than relying on a single method of valuation.
Professional Gemological Credentials
Mark’s professional background combines formal gemological education, jewelry craftsmanship, and decades of practical market experience. He is a Master Jeweler, a Graduate Gemologist with Honors from the Gemological Institute of America, and a Certified Gemologist through the American Gem Society.
His gemological education includes advanced training in diamond grading, colored gemstones, gemstone identification, and the principles used to evaluate diamonds and fine jewelry. His experience also includes the detection and separation of laboratory-grown diamonds from natural diamonds, an increasingly important skill in today’s diamond market. Understanding the visual, gemological, and testing characteristics that can distinguish laboratory-grown material from natural diamonds is essential when accurately identifying and evaluating modern diamond jewelry.
His background as a Master Jeweler adds another level of practical understanding of jewelry construction, manufacturing techniques, repair, craftsmanship, metals, settings, and the characteristics that can distinguish an ordinary piece from one deserving further consideration.
Professional and Industry Affiliations
Mark maintains longstanding connections to the professional gem and jewelry industry. He is a member of the GIA Alumni community, a member of the Jewelers Board of Trade, and a member of the Thai Gem and Jewelry Traders Association.
These industry relationships reflect a career that has extended well beyond retail jewelry and into the broader professional markets where diamonds, colored gemstones, estate jewelry, luxury pieces, and precious metals are bought, sold, evaluated, and traded.
Nearly Half a Century of Jewelry and Precious Metal Experience
For nearly half a century, Mark has been actively involved in buying and selling diamonds, luxury jewelry, estate jewelry, colored gemstones, gold, and precious metals. His experience has taken him through major metropolitan jewelry markets throughout the United States and has provided extensive exposure to changing market conditions, regional buying environments, estate collections, designer jewelry, antique pieces, and valuable items of many different types.
That depth of experience is particularly important when evaluating jewelry because value does not always come from a single component. Precious metal content, diamond quality, gemstone identity, craftsmanship, designer origin, rarity, condition, age, construction, and current market demand can all influence what an item may be worth.
International Colored Gemstone Buying Experience
Mark has also coordinated numerous gem and jewelry buying trips to Chantaburi, Thailand, one of the world’s most important centers for the trading and processing of colored gemstones.
Working within the Chantaburi gemstone market provided direct exposure to rubies, sapphires, and other colored gemstones as they move through an international trading center used by dealers, cutters, brokers, and jewelry professionals from around the world.
That experience contributes to Mark’s understanding of colored gemstones not simply as laboratory specimens, but as commercially traded gems whose value can depend on origin, treatment, quality, cutting, market demand, and many other factors.
Diamond Evaluation and Grading Expertise
Diamond evaluation requires an understanding of far more than carat weight alone. Cut, color, clarity, shape, proportions, fluorescence, condition, grading reports, and current market demand can all affect the value and marketability of a diamond.
Mark’s gemological training and decades of hands-on experience allow diamonds to be examined as individual gemstones rather than simply as components of a piece of jewelry. His expertise includes evaluating both loose and mounted diamonds, interpreting laboratory grading reports, recognizing characteristics that may affect value, and determining when additional testing is appropriate.
Modern diamond evaluation also requires the ability to distinguish natural diamonds from laboratory-grown diamonds. Mark’s experience includes the detection, identification, and separation of laboratory-grown diamonds from natural diamonds using appropriate gemological examination and testing methods. This distinction is increasingly important because natural and laboratory-grown diamonds can differ substantially in market value even when they appear similar in size and quality.
Gold, Estate Jewelry and Precious Metal Evaluation
Gold jewelry and precious metals require more than a simple weight-based evaluation. Purity, construction, condition, gemstones, designer origin, age, craftsmanship, market demand, and the potential value of the complete piece can all affect how an item should be evaluated.
Mark’s background as a Master Jeweler, Graduate Gemologist, Certified Gemologist, and longtime precious-metals buyer allows him to evaluate both the metal and the jewelry as a whole. Some pieces are appropriately valued primarily for their recoverable precious metal content, while others may have additional value because of diamonds, colored gemstones, designer attribution, antique character, rarity, or resale potential.
Estate jewelry can be especially complex because a collection may contain items from different periods, makers, countries, and quality levels. Careful examination helps determine which pieces should be evaluated as precious metal and which may deserve consideration as jewelry, gemstones, collectibles, or designer pieces.
Why Gemological Expertise Matters
When selling diamonds, fine jewelry, gemstones, or inherited valuables, correctly identifying exactly what an item is can be just as important as determining what it weighs.
Professional gemological expertise can reveal characteristics that may be missed in a basic precious-metal evaluation, including diamond quality, gemstone identity, treatments, laboratory-grown versus natural origin, antique construction, designer markings, unusual craftsmanship, and other features that can materially affect value.
A knowledgeable evaluation should consider the complete item rather than assuming every piece should be valued primarily for its metal content. The goal is to understand what the item actually is, determine which characteristics contribute to its value, and then evaluate it according to the most appropriate market.
Mark's Role at Pro Diamond Buyers
As the company leader at Pro Diamond Buyers, Mark sets the professional standards that guide every evaluation and customer interaction. He provides professional evaluations for customers selling diamonds, diamond jewelry, gold jewelry, estate jewelry, colored gemstones, coins, bullion, Rolex watches, and other valuable items.
Just as important to Mark as his own professional experience is passing those standards on to the next generation. He has personally trained his two sons, both GIA graduates, to approach every evaluation with the same standards of honesty, excellence, integrity, and attention to detail that have guided his career for nearly half a century.
Mark’s leadership, professional knowledge, and commitment to ethical dealing have helped establish Pro Diamond Buyers as a trusted local authority in gemology, diamonds, luxury jewelry, estate pieces, and precious metals. His sons continue that approach by combining their GIA education with the practical knowledge, evaluation methods, and professional standards Mark has developed throughout his career.
Together, the family brings formal gemological education, generational experience, and a shared commitment to accurately identifying and evaluating valuable items. Customers benefit from a team that understands not only diamonds and precious metals, but also craftsmanship, designer jewelry, colored gemstones, antique and estate pieces, and the many factors that can contribute to an item’s true market value.
Evaluations are conducted in a private, appointment-only environment at the Pro Diamond Buyers office in Folsom, California, where customers can receive straightforward information about their items and decide whether they wish to sell without pressure or obligation.
Educational Resources by Mark
Mark also contributes educational resources designed to help consumers better understand diamonds, gold, jewelry, gemstones, precious metals, and the evaluation process before deciding whether to sell valuable items.
These resources draw on nearly half a century of practical buying experience, formal gemological education, jewelry craftsmanship, and direct involvement in both domestic and international gem and jewelry markets. The goal is to provide clear, useful information that helps consumers understand the factors professionals consider when evaluating valuable items.
Professional Evaluations at Pro Diamond Buyers
If you are considering selling a diamond, diamond jewelry, gold jewelry, estate collection, colored gemstone, Rolex watch, coins, bullion, or other valuable items, Pro Diamond Buyers provides professional evaluations based on gemological knowledge, market experience, jewelry expertise, and careful examination of the complete item.
Under Mark’s leadership, the team combines formal GIA education, generational experience, and decades of practical buying knowledge to evaluate valuable items as completely and accurately as possible.
Pro Diamond Buyers serves customers throughout Sacramento, Folsom, Roseville, Auburn, Placerville, Elk Grove, and surrounding Northern California communities from its private, appointment-only office in Folsom.