World Of Gems Conference 2017 Proceedings Book

WORLD OF GEMS CONFERENCE V - 22 - SEPTEMBER 2017 diamond auctions. Otherwise, smaller auc- tion houses or diamond brokers are the best option for quick disposal. Next you will deal with the colour. Start by sorting them into basic colours. This is the bit that is deeply satisfying. You can just kind of zone out and become all zen doing this, but you have to be strict. The problem is that as a gemmologist you don’t just see red, you see slightly orangish red, or brown red or pinkish red, leading to chaos! You have to be strict and just pull all the reds out, then all the greens then all the blues, etc., until you have your basic piles of red, pink, orange, yellow, green, blue, purple, white, black, iridescent and multi-coloured, hardstones and every- thing else, rubbish, metal glass beads, dirt, etc. Figures 1-3. Once you’ve done that you can then further sort each colour into sub colours, either by type of colour or type of stone, for instance blues get sorted into sky blue, medium blue and dark blue, reds get sorted into ruby type reds, purplish garnet type reds, brownish garnet type reds and red tourmaline type reds. At this point you’re back to looking at what’s going to make you the most money; what do you want from the stones? The vast ma- jority of commercial low quality, low price gemstones, have very low resale potential, and get sold at an auction stones for tender sale by colour in bulk, for example 2,000 grams of blue stones, described as “con- taining sapphires, aquamarine, topaz, paste, and other natural and man-made gem- stones.” In each colour there will be stones of value that you need to find. For instance in yellow, you want sapphire and beryl not quartz and glass. As an example of how I screen the parcels for stones of value I will use the sky blue pile as an example. In the sky blue stones, the only stones that consistently make a lot of money are the aquamarines, so that’s what I’m looking for. Everything else you just want to pull out, anything I can identify and sell as a described parcel or single stone is a bonus. The stones generally in this parcel are: blue topaz, synthetic spinel, glass, aquamarine, zircon, CZ, coated topaz/coated quartz, treated quartz, tourmaline, apatite and diamond, in that order of volume. You start by pouring the stones onto a sorting pad and just raking through them. Doing this you are likely to recognise zircon, treated quartz, tourmaline, apatite and diamond by their characteristic appearances. They all have their own key features that you recognise even when tumbled about on a sorting pad, zircons for instance have a characteristic green- ish blue and high dispersion, glass has rounded edges and are warm to the touch. The two that are really hard to tell apart by eye are topaz and aquamarine, which is why I then move on to testing. When it comes to testing I always start with polariscope, I have found it to be invaluable tool in TREASURE FROM TRASH FIGuRE 4. Double refraction. FIGuRE 5. Anomalous double refraction. FIGuRE 6. “Tabby” extinction.