Guide to buying rough gemstones

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Buying rough gemstones can be very complicated and confusing for buyers.  This guide offers some notes which may help buyers purchase wisely.  The recommendations apply broadly to most gemstones but we discuss sapphire in more detail where relevant.   Price may range from very low to extremely high so here are a few things to consider when trying to decide if a particular piece of rough is good value.

There are broadly three main types of rough: facet rough, cab rough and specimen or collector rough. Of course in reality, there are hundreds as every piece is unique. 

The first and most widely used is facet rough. When purchasing facet rough online you should be aware of the following:

1. Pictures are usually magnified so buyers can have a better view of the stone (a kind of "virtual loupe"). This will obviously make the stone appear much larger than it really is. To avoid being surprised when you receive your purchase, we recommend that you carefully check the dimensions given for a piece of rough. A useful tip is to sketch it on paper to get a real idea of the size. Carats are used to indicate weight (remember that there are 5 carats in 1 gram) and dimensions are usually given in millimetres.

2. Pictures may be enhanced to make the stone look much better than it is in real life. Honest sellers will only ever adjust pictures in order that the image matches the colour seen in real life as closely as possible. Colour may vary between computer monitors and under different lighting conditions but the aim with gemstone photography is always to present the most accurate image possible.

Unfortunately, a dishonest seller can tweak the photographs so drastically that it bears little relation to the rough you are buying. Difficult to get around this problem but we recommend that you look at the photographs very carefully and look for evidence of excessive retouching. Comprehensive description of the rough including highlighting of any potential problems is a good sign of an honest trader.

Lighting is also important - excessive backlighting may indicate a stone that is quite dark.  Please note though that gemstone photography is a very specialised and difficult task - some sellers do it very well and can make a poor stone look good while some sellers are less skilled and may have good rough that looks better in real life than the photograph.

3. If it sounds too good to be true, it probably is ! Synthetic rough can be made to look just like the real thing - inclusions are now being deliberately manufactured in synthetics in order to fool buyers. We have had reports of synthetic gems being slipped into parcels along all points of the supply chain so buy carefully.  Buying as close to the source as possible reduces the chances of synthetics being slipped into the parcel - buying direct from the miner is as close to the source as possible.  Buying from a trusted seller with a rock-solid return policy will reduce your risk of bad buying.

4. Chemical enhancements are widespread in many countries. These treatments drastically change the colour of the original stone and are often still sold as natural. These gems are not as valuable as fully natural untreated rough and will not appreciate in value like a truly natural gemstone. Honest sellers will clearly specify what treatments (if any) have been done.  Unfortunately, some sellers have bought rough from sources which do not disclose treatments and this makes it difficult for them to pass information along to buyers.  However, we recommend buyers look for specific statements on treatment status for their peace of mind.

In sapphire, be especially careful of yellows, orange-pink (often described as padparascha colour) and oranges as most of these colours available in the market currently are the result of Beryllium treatment (bulk diffusion). Natural rough in these colours will be clearly identified and be priced at a premium (treatment status should be guaranteed in writing by the seller). If treatment is not mentioned in these cases, you should probably assume that the rough has been treated. Sapphire may even be coloured blue by diffusion treatment with titanium - this is less common in rough as the colour is surface only and easily detected - something to watch out for though.

5. Recovery percentages in sapphire for cut from rough is usually only around 25% ( this varies but this is a good rule of thumb). So if you are aiming for a 2 carat finished gem, you need to look for at least an 8 carat piece of rough. Recovery percentage may be lower if the piece of rough is poorly shaped - sometimes rough with excellent colour and clarity may be discounted for this reason.

6. Some shapes are harder to obtain from sapphre rough - for example larger rounds are less common as there is normally more wastage from the rough to achieve this shape. Ovals, cushions and emeralds are far more common due to the typical shape of sapphire rough. Although dog tooth crystals are often passed over, these can be cut in very attractive pears and briolette shapes - keeping in mind that colour zoning is sometimes a issue in these crystals (colour is often lighter at the crystal tip).

7. Plans for the shape and size of a cut often need to change as preforming is carried out as even the best expert can miss a hidden flaw or inclusion when inspecting the rough. Remember that this is a natural product and perfection is exceedingly rare - if you want perfect rough at bargain prices, we suggest you buy synthetic. We find though that good cutters who want their work to be interesting and challenging appreciate working with rough made by Mother Nature. Most sellers will only accept returns on rough in original condition only so please inspect your rough very carefully before starting any work.

8. Rough of most gemstones including sapphire almost always has inclusions that need to be worked around. Perfect rough is very rare and if found is extremely expensive. When buying rough online, you should inspect the photograph and description carefully - good sellers will always highlight any noteable points about each piece of rough to assist you. Feel free to ask questions before buying. A no-fuss return policy is critical when buying online but it is easier for everyone concerned if this is not necessary - the need to return rough will be far less likely if you look for detailed descriptions and ask questions before buying. Some sellers list their rough with almost no description but we suggest that you are buying at a higher level of risk in these cases.

As previously mentioned, a no-fuss return policy is critical when buying rough.  Most reputable sellers will realise that buying online is difficult and will happily refund the purchase price if you are not satisfied with the stone.  Things to look out for are excessive restocking fees - sellers are allowed to charge these but should clearly mention it in the item listing.  Note that if the restocking charge is high, it may discourage buyers from returning an unsuitable stone so better to buy carefully in the first place.

9. You normally get what you pay for. Most sellers price rough according to colour, clarity,and estimated percentage of waste. Therefore, in most cases, paying slightly more per carat will work out cheaper in the long run.

Cab rough should be much cheaper than facet grade as it has some inclusions, may be a darker colour or is less transparent (translucent or opaque instead of fully transparent).

Star sapphires are sometimes achieved from this type of rough but are rare and difficult to pick and take some skill on the part of the cutter to achieve a good star. Much of the rough being sold on Ebay as suitable for cutting star sapphire will be disappointing - dont buy a pound of this stuff at bargain basement prices and expect every piece to produce a star.

Note that diffused star sapphires are very common in the market and are extremely cheap. These are produced by a treatment on the surface of the finished gem and are worth only a fraction of the value of a natural star sapphire.

Cabs are great fun as they are cheaper and faster to make, quick and easy to learn and can produce a fantastic, attractive gemstone.

Some rough is far more valuable in its natural state and may never be cut.

No two pieces are ever the same and price is determined by rarity along with other factors such as large size, interesting or unusual shape and colour, type of inclusions, etc. Dog Tooth sapphire crystals are a good example of ones to collect as these come in a variety of forms with interesting appearance.

It is less common for this kind of rough to be offered on Ebay as these keen collectors have many good contacts for direct sales.  However, a number of sellers do offer interesting pieces from time to time and it is good idea to save these in your favourites so you can keep a close eye on their offerings.  Sometimes, these rare and unique pieces are snapped up very quickly.  Ebay now offers facilities such as RSS feeds with which to keep up to date with listings from your favourite sellers.

The easier and best resources of the worlds sapphire have already been mined. New areas will be discovered but the chances of bulk amounts of higher quality rough coming back on the market are low. Prices for rough sapphire are very low by historical standards so any sensible purchase of good quality natural sapphire should increase in value from current levels.

Often, if you need a specific size in a finished gem, it may be better to purchase a cut gem to your specifications. This way, you know exactly what you are buying without the risk of a piece of rough not cutting as expected. However, there are very many hobby lapidaries and custom cutters who need a dependable supply of rough.  We recommend developing a relationship with some trusted sellers who offer the kind of rough that works well for you.  Remember that Ebay is a big marketplace though with new sellers starting up all the time so keep an eye out for new sources - as always, read feedback carefully and ask questions before buying if necessary.

One last point - some sellers offer both cut and rough gems even though cut gems are worth much more per carat than the rough.  Some buyers find this confusing but in the gemstone market, we find there is good demand for quality pieces of rough in small lots or individual pieces while the market for cut gems is supplied well and these items may be slower to sell. Some sellers have good inventory of cut gems and do not need to cut every piece of good rough that they come across so do not assume that the rough is somehow inferior just because of this reason.  Dont treat it like a lucky dip though - check carefully and buy wisely.

Hope this article has been of interest.
Thank you from Aussie Sapphire

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