Our 'FOUR C’s' guide to purchasing a diamond

    Purchasing a diamond for the first time can be a daunting experience. At SJ & Co we aim to make it an amazing and truly memorable one. Using our 25 years of experience we will give you the very best advice and guidance to inform your selection and ensure you enjoy finding exactly the right diamond for you.


    Is the first in the four very important C’s and in our opinion is only matched in importance by cut. The colour is the whiteness or the lack of colour in a diamond. D is the finest colourless diamond there is and it continues all the way to Z yellow. At SJ & Co you will only ever purchase a diamond D-H colour, for the reason that we only manufacture the finest quality. The whiteness or lack of colour of a diamond is what you initially see so why not have the best.

    Quality of diamond colours used at SJ & Co are shown below:

    D E F G H
    Colourless Near colourless



    People confuse the cut of a diamond with shape (round, princess, cushion, etc).

    Cut is the brilliance of a diamond and the measure of how good the symmetry, proportion and polish of a diamond is and how it appears to the eye. The cut grade is the important factor once you have decided on colour, our advice is to chose no lower then good. There are five grades of cut from the GIA: poor, fair, good, very good and excellent. At SJ & Co we only use good, very good and excellent. These cuts of diamonds are classed as ideal or excellent cut and really do give a diamond its overall brilliance so why not have the best.

    Quality of diamond cut grades used at SJ & Co are shown below:

    Good Very Good Excellent



    Clarity is important but to us not such a critical factor when making that all important purchase, unless your budget allows. It all comes down to rarity and F flawless is the rarest so naturally it comes at a very high premium. Clarity grading starts at F through to I3, at SJ & Co we manufacture from F to SI 2. Apart from carat size clarity is where you will find big differences in prices, and visually to the naked eye nothing significant? Under 10 x magnification a trained diamond expert or jeweller will be able to pick up the clarity or as we would say Mother Natures fingerprints.

    Exceptional value for your money is VS-SI clarity.

    Quality of diamond clarities used at SJ & Co are shown below:

    F IF VVS 1 - VVS 2 VS 1 - VS 2 SI 1 - SI 2
    Flawless Internally flawless Very very slight inclusion 1
    Very very slight inclusion 2
    Very slight inclusion 1
    Very slight inclusion 1
    Slight inclusion 1
    Slight inclusion 2



    The word carat originally comes from the word “carob” The carob seed was used as a counter weight to weigh precious stones. A carob seed weighs 0.2grams so that would equal one carat. So carob seeds became the perfect choice in ancient times to weigh precious stones.

    The carat is the overall weight of the diamond, there is 100 points to 1.00cts, 5.00cts to 1 gram. So 0.50cts or half a carat that is half of 1.00cts.

    So a 1.00cts diamond is one fifth of 1 gram or 200 milligrams
    (0.01cts = 1 point)
    (0.25cts = 25 points or quarter of a carat)
    (0.50cts = 50 points or half a carat)
    (0.75cts = 75 points or three quarters of a carat)
    (1.00cts = 1 carat)

    Naturally people say the bigger the diamond the better yes that is true if all the other C’s are the best and money is no object, but if you have a big carat weight and the rest of the C’s are mediocre. In our opinion you would be better of going for a slightly smaller carat, whiter colour, better cut, and slightly lower clarity remember S.I clarity you cant see to the naked eye. In our opinion quality always before quantity.

    This is only our opinion and our honest view on how to purchase a diamond.

    Every jeweller and diamond expert has different ideas and views. So does every customer its all personal preference at the end of the day.

    At SJ & Co we manufacture jewellery for that special occasion or memorable moment in life. Only the finest diamonds are chosen, So allow yourself the best.

    Our interactive guide

    Our Diamonds

    At SJ & Co we can supply you with any diamond from 0.30cts upwards, D to H colour and I.F to S.I. 2 clarity.   All the diamonds we manufacture in jewellery come with a GIA certificate.

    When purchasing round brilliant cut diamonds all diamonds will be cut very good and above.  For triple excellent round brilliant cut diamonds there is an extra charge, please state when purchasing if you require such a stone.

    Princess cut and Fancy cut diamonds will be cut good and above. Fancy colour diamonds from 0.10cts upwards come GIA Certified

    All diamonds we use and supply are conflict free and non-fluorescent.