A little bit about us...

J. Thomas Jewelers in Sparta, New Jersey is family owned and operated by Leonard & Liz Girardo. For over 30 years, Leonard have Liz provided a comfortable atmosphere while offering the finest quality and selection at the most competitive prices.

Together they travel the world attending jewelry shows and events to guarantee that their clients have the newest and most exciting designs available to them. In order to guarantee that J. Thomas Jewelers are competitive with diamond prices, Leonard deals directly with a diamond cutter and, therefore, eliminates the middle man. These savings are automatically directed to your diamond purchase.

Our staff has all been trained to offer that warm and welcoming environment. You will be treated with personal attention by GIA trained sales pros, all qualified to address any aspect of your jewelry needs.

We provide luxury and value at J. Thomas Jewelers!

Our Services

  1. Appraisals - We specialize in appraisals on jewelry, diamonds, gemstones, watches and more.
  2. Engraving - We offer expert hand and precise machine engraving.
  3. Pearl/Bead Stringing - We can repair any necklace or bracelet, graduated or multi strands.
  4. Jewelry/Watch Repairs - Our repair staff are experts in repairs of all types.
  5. Custom Designs - Let J. Thomas Jewelers become your own personal designer.

Jewelers of America

J. Thomas Jewelers is a member of Jewelers of America (JA), a national association for the retail jeweler. JA is both a center of knowledge for the jeweler and an advocate for professionalism and high social, ethical, and environmental standards in the jewelry trade.

The JA mission is to assist all members in improving their business skills and profitability. JA will provide access to meaningful educational programs and services, leadership in public and industry affairs, and encourage members with common interests to act in their and the industry's best interests.

4 C's of Diamond Buying


Many people confuse cut with the shape of the diamond. Ths shape you select is a matter of individual taste and is only limited by the skills of the craftsman. The cut is the most critical of the 4 C's because the quality of the cut affects the value of the diamond. In determining the quality of the cut, the grader evaluates the cutter’s skill in the characteristics of the diamond. The more precise the cut, the more captivating the diamond is to the eye.


Diamonds can have natural characteristics known as inclusions or external characteristics known as blemishes. The clarity of a diamond is defined by its natural characteristics and is graded by using a 10 power (10x) microscope. The most valuable and rare diamonds have no natural characteristics at 10x magnification.


Gem-quality diamonds occur in many hues. Colorless diamonds are the rarest. Other natural colors (Blue, Red, Pink for example) are known as fancy – their color grading is different than from white diamonds. The GIA color grades range from D (colorless) all the way to Z (yellowish-brown).


The carat is the diamond’s physical weight measured in metric carats. One carat equals 1/5 of a gram or .007 of an ounce and is subdivided into 100 points. For example 1/2 carat is .50 carat and expressed as 50 points. Carat weight is the most objective of the 4 C's. It involves no estimates, comparisons or judgments.