Hi Milly
There's a whole thread on Emerald buying somewhere - can somebody dig it out for Milly please? It may have been in the TJC section of the forum. In the meantime however .............
1. Colombian Emeralds are considered the best. There are good and bad Colombian Emeralds (just like all gemstones)! So there are also very good Zambians and if you compare a good Zambian to a rubbish Colombian, of course you'd be better off with the Zambian.
2. Zambians tend to be more bottle green than the blue/green of Colombians. Colour in Emeralds is important but ultimately you need to find the colour you like!
3. Clarity is another issue with Emeralds. Inclusions are expected with Emeralds BUT they should NEVER detract from the beauty of a gemstone. So, if it looks cracked and crazed or it has black spots etc, it's not good. The less inclusions the better! Also, anything that looks milky or cloudy is not good. An Emerald should be clear looking, not opaque. If it looks like a cough sweet then it'll be valued at about the same
4. The most important issue with Emeralds is treatment. Oiling is accepted and 95% of Emeralds are oiled. This practice dates back to Egyptian times and is considered normal and nothing to worry about. Then you have filling of Emeralds. There are different degrees of filing and different fillers. Some you may find acceptable and are stable and have a longevity. Others haven't. Dyeing of Emeralds and composite Emeralds (i.e. sticking pieces of Emeralds together to get a bigger gemstone) are really really not acceptable to lovers of Emeralds UNLESS the price point reflects what's been done. However, there are more and more highly treated Emeralds on the market. If the price is low it means that they are affordable to more people (a good thing) but they won't be an heirloom piece and, without the proper care, also won't last. So it's important to know what you're buying and then assess whether you believe it's a fair price.
5. Lastly, the care of Emeralds is critical. Although not particularly low on the MOHS scale, they do chip and fracture (partly because of their internal structure). So, for example, hot water can crack them, putting them in a sonic cleaner COULD remove all the filler and dry them out, knock them in the wrong place and you'll have a pair for earrings (that may not be a matching pair).
Having said all of that, I am a lover of Emeralds. One of my most treasured rings is an untreated Emerald that I inherited that has very few inclusions and a superb colour. My Mum wore it for nearly every day of her married life BUT treated it with care (she knew how to treat her jewellery) and it's survived. So, if you find one you love, get it and enjoy it!
Hope that helps and pictures WILL be needed if you buy one. x
