Gemstone Buyer’s Guide

When looking for jewellery to buy, it is important you know exactly what it is you’re buying. So, we feel it’s important to make sure our customers have the most accurate and honest information presented to them when enquiring about an item. However, if you are new to the market and looking for something specific, there are a few aspects to bear in mind when choosing the right gem for you.

Every gem on our website is listed with a certificate of authenticity to reassure the customer that the items in question are, in fact, certified and legitimate. Included within these documents are four major categories which determine the value of the item. These are commonly referred to as the 4C’s; Colour, Cut, Clarity and Carat. Each factor heavily determines the price of the asset, whether that’s positively or negatively.


Depending on the type of gem you’re interested in, colour is almost always the first, most obvious indication of value. For example, diamonds are more valuable when the absence of colour is more prominent. Colourless diamonds are extremely rare, these are considered D grading, whereas most diamonds available in the current market are of a lesser grading. However, gems such as Sapphires, Rubies, Emeralds and Tanzanite’s, with their popularity coming from their signature colour, become more valuable when the presence of colour is more obvious. For example, when valuating a Ruby, the price is heavily increased the deeper the colour red appears.


The cut of a diamond refers to how well the diamond interacts when light is refracted within the gem. So, the more light that is transmitted, the higher the value. This varies from gemstone to gemstone. There are many shapes that a gem can adopt once cut; ovals, cushions, pears etc. which is often decided based on the demand for that shape, but it is the quality of the cut that gives each gem its value. Achieving symmetry is key when the rough gems are being cut, this can sometimes be identified by the naked eye, depending on the size of the gem, otherwise, a loupe is the most popular tool to use when inspecting jewellery up close.

Clarity & Carat

Judging the clarity of a gem means considering the volume of inclusions and imperfections in the gem. This is graded from flawless (extremely rare, and the most valuable type of gem), to I3 (with the most obvious and highest volume of inclusions. Wherever your gem lies within this chart, the value is affected.

A carat is a type of unit used to measure the weight of a gem. Usually, a carat is 1/5th of a gram. If the carat increases so does its value.

Having stated the methods used to evaluate a gem, there are various other factors to consider when purchasing which will be dependent on the buyer’s taste, and therefore affect your own appreciation of the stone. Some of the factors to consider away from the more traditional strategies may include: the personality of the wearer, whether it’s a gift or for an engagement, personal taste in colouring, cut etc. So despite the amount of market research, valuations or certificates that are shared with the customer, it always boils down to one’s preference.

With this in mind, a lot of jewellery is bought as a gift – most commonly as a birthday gift. Birthstones play a massive part in this specific market sector; each month has an assigned gemstone to represent the period of each zodiac, according to astrologers. They are said to bring aspects of power and protection to those who wear theirs. Within this David Jerome collection, we have 5 of the 12 traditional birthstones, perfect if you are looking for the ideal gift.

There are certain occasions that are also deserving of this calibre of jewellery – Wedding Anniversaries. Typically, the 10th Anniversary is usually celebrated with the gift of a diamond, the 40th Anniversary is a Ruby, the 45th Anniversary is a Sapphire and the 55th Anniversary is an Emerald. Of course, this isn’t a set ‘rule’ and usually, one’s taste comes before trends, so it’s important to consider the wearer’s own preference, whether that be your own, a friend’s or a family member’s. There is a huge range of beautifully crafted rings, each designed by hand by David Jerome, that play the part of the perfect final accessory to your favourite dress, suit, gown, or cocktail dress.