Premium Diamond Suppliers

For the vast majority, purchasing a diamond engagement ring is an occasion that is full of pressure and uneasiness. A number of jewelers in the market use traps and tricks structured to deny you of significant worth and put more benefit in their pockets.

Jonathan K. & Co has condensed the knowledge we have gained from working with the largest diamond manufactures in the world. Learn from us on how to avoid common mistakes and obtain the most value on your purchase. Here we will teach you how to find the optimal color and clarity combination specifically for the shape you desire. This will allow you to get the most brilliance out of your diamond. 

Specializing in Natural Diamonds

We are honored to share the special moments of crafting the perfect piece of jewelry and what it means to you. We are willing to work with any budget large or small. Your special moments should not be defined by price.

If you are in the market for a larger diamond, Jonathan K. & Co Fine Jewelry is the right choice. With the many factors involved in purchasing a large diamond, Jonathan K. will assist you with his expertise in finding the perfect diamond for your investment. 

All Shapes and Sizes Carried









GIA Certified Diamonds

A GIA certified diamond has been graded by the Gemological Institute of America and supplied with a grading report and often a laser inscription on the girdle for identification.

Why GIA?

In the jewelry industry, the GIA is at the forefront of diamond certification companies. They are recognized by their proven consistency in strict grading standards. When purchasing a diamond with a GIA certification report, it provides the peace of mind that the diamond’s quality is the most accurately represented.

Lifetime Diamond Upgrade

At Jonathan K. & Co Fine Jewelry you have the opportunity to upgrade any certified diamond purchased through us. 

No Minimum

The catch with most diamond trade up programs is you have to spend a set minimum amount more in order to upgrade. At Jonathan K. & Co Fine Jewelry, you have the ability to trade up any amount for any reason. This includes all large certified diamonds, diamond stud earrings, and single diamond pendants.

Diamond Buying Guide

What are the 4C's?

The 4C’s represent the cut, color, clarity, and carat weight of a diamond. The 4C’s were created to provide a universal language to communicate the quality of diamonds, and buyers can know what exactly the make of their diamond is.

Our 5th "C" - Confidence

The 4C's


A diamond’s brilliance is largely determined by its cut. An expertly-cut diamond with perfectly symmetrical and aligned facets will reflect light beautifully, leading to unrivalled brilliance. True expertise is required to create facets with perfect proportions that maximise light and increase a diamond’s signature sparkle.


White or colourless diamonds exist on a scale of many different shades, ranging from brilliant white to pale yellow. These subtle differences are graded on a colour scale from D (colourless) to Z (light yellow). Beautiful coloured diamonds, in hues of yellow, pink, blue, orange, green and red, for example, go beyond all other measures of rarity, and a graded based on their intensity and enticing depth of colour.


Diamonds are created by tremendous heat and pressure deep within the earth. This thoroughly organic process means that virtually all diamonds contain internal inclusions and surface blemishes. Diamonds with fewer of these characteristics are deemed to have a higher clarity, ranging from FL, or Flawless, to I, signalling a number of inclusions.


In the ancient world, carob seeds were used as a reference for the weight of individual diamonds. Today, this historic practice has led to the word carat, which is now the contemporary measure of weight for all diamonds. Precise measurements are taken to the hundredth decimal place to ensure complete accuracy. A metric ‘carat’ is defined as 200 milligrams.