Uwe Koetter is pleased to offer its clients a variety of semi-precious and precious stones in a dazzling array of colours, shapes, sizes and cuts.

Should we not have your desired stone in our inventory, we will gladly source it from our global network of partners.

Uwe Koetter’s 5 C’s


Every semi-precious or precious stone needs to be perfectly-proportioned in order to reveal its true beauty, irrespective of whether a princess, an emerald, an oval or (the perennial favourite) classic round cut is chosen.

A badly-cut or proportioned stone can reduce the value of a diamond (or any other stone for that matter) by up to 40%. Therefore, regardless of which colour, clarity or carat weight you choose, always ensure you select a perfectly-proportioned stone.

Cut Untitled-4-Recovered


The diamond colour scale ranges from D (where diamonds are colourless) to Z (where diamonds are light yellow). Thereafter diamond colours are depicted on a fancy colour diamond scale. Those who prefer a colourless diamond should select a stone in the D-F range. Near-colourless diamonds which have been graded between G and J offer good value as their colour is typically undetectable to the naked eye.

Some diamonds display overtones (secondary colours such as brown and grey). The presence of an overtone may be complimentary to a diamond, but it is also possible for the overtone to decrease the beauty and value of the diamond.

It is vital to note that some laboratories will not make the presence of overtones known on the diamond’s certification, as a diamond possessing an overtone and one without could be classified in the same category.

It is possible for the presence of fluorescence to enhance the visual appeal of a diamond with a lower colour rating in the J through M range. The fluorescence helps to cancel out any faint yellow in the stone, resulting in a colourless appearance. However, fluorescence could also cause a stone to appear milky.

Naturally-occurring diamond colours include grey, white, blue, yellow, orange, red, green, pink, purple, brown and black.



The fewer imperfections a stone possesses, the greater its clarity will be. This results in a more brilliant and valuable stone with the most valuable of these (due to its rarity) being referred to as a Flawless (FL) stone.

Depending on their budget and preference, Uwe Koetter clients are advised to select a diamond within the FL through to SI (Slightly Included) range. Certain diamond cuts (the emerald cut in particular) demand a diamond with the highest clarity, as a simplicity of cut reveals the diamond’s inclusions more readily.

stone clarity 2Clarity renata 


The “carat” represents the weight of a diamond (one carat = 100 points = one fifth of a gram). Diamond prices increase with diamond carat weights, because larger diamonds are more rare and are deemed more desirable. However, two diamonds of equal carat weight can have very different values and prices depending on three

other factors: clarity, colour and cut of the diamond. It is important to keep in mind that a diamond’s value is determined by using all elements of the diamond, not just the carat weight.



On purchase of a diamond or other stone from Uwe Koetter, the client will receive an Uwe Koetter valuation certificate. This serves as a guarantee that clients receive what they paid for. Furthermore, some diamonds and tanzanites also warrant the issue of an internationally recognised diamond grading laboratory certificate.



Jewellery Care


Here are some guidelines to help keep your diamonds in tip-top condition:

  1. Diamonds must be kept clean and stored carefully when they are not being worn.
  2. If you notice loose stones or any other damage to your jewellery, it is best not to continue wearing it. Kindly bring it to us so that we can assess and repair it for you.
  3. We recommend that you have all your jewellery settings and gemstones checked once a year.
  4. When you are not wearing your diamonds, be sure to store them in a fabric-lined case or in a box with dividers to prevent the diamonds from scratching.


Packing your precious diamond jewellery for travelling should be done with the utmost care. There are many types of carry cases that are specifically designed for jewellery travel. These are available in all price ranges, sizes, shapes and designs. Most have velvet pads inside to attach pins and earrings to, with special compartments for bracelets and necklaces.


Diamonds, like anything else become dusty. Lotions, powders, soaps – even the natural oils from your skin – will create a film on your diamonds, which will reduce their brilliance. Furthermore, chemicals in the air will oxidise or discolour the mountings. Keeping your jewellery clean will maximise its brilliance.

Here are three ways to clean your diamonds:


Prepare a small bowl of warm soapy bubbles using a mild household liquid detergent (be sure not to use any cleaners containing chlorine). Clean the jewellery with a soft brush until you have created a lather around it. With the jewellery on a plastic or metal strainer, rinse it off with warm water (be sure not to clean your jewellery directly over the drain). Pat your jewellery dry with a soft, lint-free cloth.


Prepare a solution of 4 parts cold water and 1 part dishwashing detergent. Soak the items of jewellery you wish to clean. Remove the jewellery from the solution and drain on tissue paper.


There are a variety of liquid jewellery cleaners formulated specifically for the kinds of metal and stones found in your jewellery which makes cleaning your treasures easy. Be sure to follow the instructions carefully so as not to cause any damage.


  1. Avoid wearing your diamonds whilst doing housework, gardening or any other kind of rough work as a hard blow could chip it. (Please be especially careful with tanzanites as these are particularly soft stones.)
  2. Never allow your jewellery to come into contact with chlorine bleach.