Category Archives: Global Diamonds Articles

Birthstone for June – The Pearl


Birthstone for October – Tourmaline


Birthstone for September – Sapphire



Birthstone for August – Peridot

peridot 2


Birthstone of the Month July – The Ruby

Ruby - July's Birthstone

Ruby – July’s Birthstone


Birthstones by Month


At Global Diamonds, we love to make purchasing the right gift an easy choice. Here’s the list of Birthstones by Month to help you find the perfect stone for your loved one.

Gemstone chart-page-0

Synthetic and Man-made Diamonds vs Natural Diamonds

Round brilliant polished diamonds.We often get comments from customers asking why they should by a real diamond vs a man-made diamond. Their argument often involves the following points:

  • A man-made diamond is much cheaper than a real diamond
  • A synthetic diamond has more brilliance than a real diamond (particularly Moissanite)
  • A man-made diamond is almost as hard as a real diamond (paricularly Moisannite)

Well here is our typical answer to dispel a few myths…

A man-made diamond or synthetic diamond is in cases much cheaper than a real diamond, however they are well over priced for what hey are. Many years ago we saw the introduction of Cubic Zirconias which were cheaper than diamonds but still well over priced for what they were. They have now come down to their true value at about $5 for a bucket load of them. So the price argument becomes redundant, a man-made diamond will always fall back to its natural price, which is unfortunately about worthless. We see people come into our store all the time where they purchased a diamond many years ago for say $200 which the diamond is now worth say $5000. The Cubic Zirconia they bought years ago for $50 in now worth Nil.

The second point is the claim man-made/synthetic diamonds have more brilliance than a real diamond (particularly moissanite). The truth here is that they do, but diamonds have never claimed to have the highest refractive index on the earth. The beauty of the diamond comes from the unique refractive index that it does carry. Nice and brilliant, but it doesnt look like you have a disco ball or rainbow on your finger. So for the Moissanite manufacturer to claim that their product has a far higher refractive index than diamonds, is to claim their product looks nothing like a diamond, so why do they call it a synthetic diamond??

The last point is the hardness of Moissanite vs Diamond. In the official Mohs scale of hardness, a diamond carries the top level 10 out of 10 and Moisannite carries approx 9. This seems to be close, however the scale is not one of a straight line, rather it increases exponenitally. In simple terms, a diamond is up to 100 times harder than its nearest man-made or synthetic creation. Number 9 in the Mohs scale is closer to number 1 than it is to the top level 10.


Coloured Diamonds: Good, Bad, or Fad?

Round brilliant polished diamonds.When most men consider purchasing a diamond engagement ring, they automatically picture a colourless diamond, and rightly so. Colourless diamonds are the most popular and perhaps most desirable of all diamonds, but they aren’t the only stones available. Diamonds occur in a variety of different colours that can be extremely appealing to many women.

So, why if they are so fabulous, haven’t you heard much about them? Could it be they are just a fad? Let’s find out.


The Truth About Coloured Diamond Rings

  • They are Rare- One of the main reasons coloured diamond engagement rings are unique and not generally seen is due to the fact that they are actually rather rare. Now, there are stones which are enhanced artificially, but that’s not what we’re discussing.
  • They Come in Various Colours- Coloured diamonds can be found in a variety of colours, including blues, greens, blacks, purples, and yellows. The rarest diamond colour is pink, and is only found in the Australian Argyle diamond mine, which is a mine that produces all but 5% of the diamonds in the world. Regardless of their colour, these diamonds are made by forming near mineral deposits. The type of deposit and the position of the deposit determines the colour of the diamond.
  • Their Use is Affected by Prejudice- While these diamonds are beautiful, especially when used in engagement rings, many individuals are not keen on them. This is because they have been taught that white, or more appropriately, colourless diamonds are the best. While colourless diamonds are indeed beautiful, it never hurts to add a bit of colour to your world.
  • Some Coloured Diamonds Didn’t Start Out Beautiful- Because diamonds that have colour are generally more expensive and rare, many individuals use colour enhancement to bring out the colour, or change the colour, of their diamonds. This process is risky to the diamond, however, and some diamonds cannot be enhanced.

While fashion trends do tell us whether or not wearing coloured diamonds is ‘in style,’ these beautiful diamonds should not be considered a fad. Rather, they are unique gems that are part of the vast and beautiful diamond family.

If you are thinking of purchasing a diamond, don’t let the latest fads or trends be a part of your diamond decision. Whether you are looking for a colourless stone or something a bit unique, it’s a highly personal decision. If you are unsure, the traditional, colourless diamond in a round cut is by far the most brilliant of all. You can’t go wrong with that one.

Gemstones – Tanzanite

Here’s the first in a series of posts about some of the beautiful gemstones we have in store. Today’s featured gemstone is the Tanzanite.


The Tanzanite, found only in the Simanjiro district in Tanzania, was made famous by Tiffany & Co in the 1970s. Geologists believe that the chemical environment required to form the beautiful blue gem is so unique, chances of finding the same conditions elsewhere in the world are next to impossible. Experts estimate the probability of discovering another Tanzanite deposit is less than one in a million. The current source will run out within 10 years, after which time it will become unavailable as a new stone.
The natural colour of the Tanzanite is Blue, under artificial light it will have a slightly purple hue. Small stones are the most common size, a larger stone is rare.

We believe that Tanzanite would be a perfect investment stone, as the value will continue to increase. Perhaps the perfect gift for your children’s future financial security?

We would be happy to discuss any questions you may have either in store at 17 Rathbone Street, Whangarei, by emailing or by telephone on 0800 100 766

Treatments That Can Change Diamond Colours

8179-8181 copyWhen you purchase a white diamond ring, one of the factors that affects its value is its colour. The whiter the diamond, or the more colourless it is, the greater its value will be. The whitest diamonds allow a greater amount of light to pass through for a better sparkle and shine. These diamonds are rare, unlike diamonds with brownish or yellowish tones.


Fancy coloured diamonds are also extremely rare and expensive, but are not colourless. Instead, these diamonds are at the other end of the spectrum. Their value actually increases with their colour, which can range from bright yellow to blue to green.


The diamonds for your engagement rings are rated on an alphabetical scale, with D being the highest rating a white diamond can receive. The most expensive white diamonds are generally rated D, E, or F, while those with traces of brown or yellow in them are rated farther down the alphabetical scale, all the way to Z.


Because colourless diamonds are much more valuable, the jewellery industry has created a few methods for turning those lower scale diamonds into ones that are slightly more fancy. While some of these methods have been around for quite some time, others have only recently been developed.


Diamond Treatments


Colour Tricks and Coatings


Sometimes, the diamonds in your engagement rings may be covered with a coating that makes it difficult to see yellow traces in the diamond. This coating is applied with heat, but will eventually wear off over time.


Coloured dots of blue or purple ink can be painted onto diamonds to reduce the amount of yellow you are able to see. These dots are generally placed in areas that are obscured by the engagement ring setting, and are not permanent; they can generally be removed with cleaning solutions and water.


These diamond treatments are often not revealed to buyers before they make a purchase and are often used to deceive them.


Irradiation and High Heat


Sometimes jewellers turn ho-hum diamonds into fancy coloured diamonds through the use of irradiation, or exposing the diamond to radiation, and high heat. Most often, if the diamond isn’t exposed to high heat again during its life, the diamond will remain the fancy colour.


This trick generally isn’t used to deceive customers, but instead to allow those who can’t afford the price tag on fancy coloured engagement rings in NZ the opportunity to have a beautiful coloured diamond. However, those who purchase this kind of diamond need to understand that it is not a natural fancy coloured diamond and is not an investment.


High Pressure High Temperature (HPHT)


This controversial way of changing the colour of the diamonds in your engagement rings in NZ isn’t new, but the way the process is being used is. When this technique, which is similar to irradiation and high temperature treatments was first used to turn diamonds with yellow traces into fancy coloured ones, it is now capable of turning browning diamonds into colourless and expensive diamonds.


Steps are continually being taken to ensure that every buyer of engagement rings receives full disclosure about their diamonds and is not tricked into purchasing a diamond that has been artificially altered. The diamonds that are altered now must be laser inscribed with “irradiated” or “HPHT processed” or the name of a registered user in order to actually be graded.



While you may have thought a diamond was simply a diamond, when you purchase an engagement ring in NZ, you need to understand that some diamonds are altered to increase their value. Make sure you obtain full disclosure on your diamond ring so you can be sure you are buying the right one.