| In the business of buying and selling | | | | do blue sapphires look better/worse? |
| precious stones there are a number of little | | | | |
| tricks picked up along the way, tricks that | | | | All agreed that the color appearance of |
| often make the difference between profit and | | | | rubies and blue sapphires changes in the |
| loss. Collectively, we might call them | | | | course of a day, and all specified what times |
| "experience," for that is normally how they | | | | those stones look best/worst. But, to the |
| are acquired and the price is, usually, high. | | | | authors' astonishment, there was no consensus |
| "Experience" of this sort is not found in | | | | as to what those times are. This was all the |
| gemological texts; it comes only through hard | | | | more interesting in that a few stated that |
| knocks - i.e., buying stones from someone who | | | | they try to coordinate their buying/ selling |
| has a bigger box of experience than your own | | | | of these stones with the time of day in which |
| - or, via a bit of friendly advice passed on | | | | the color appearance was best (= selling) or |
| by one who has been there before. Most | | | | worst (= buying). |
| dealers have a collection of this | | | | |
| "experience," kept in a box at the back of | | | | Spurred on by curiosity, the authors and two |
| the safe or in some dusty drawer. It amounts | | | | other AIGS staff carried out their own |
| to the small pile of gems which are | | | | experiments. A selection of rubies and blue |
| unsalable; the gems you have learned valuable | | | | sapphires of mixed "type categories" (see |
| lessons by buying. In other words, gems you | | | | Sersen, 1988) was periodically examined for |
| should not have bought in the first place. | | | | two weeks. North and east window lighting was |
| | | | used. Weather conditions during this period |
| One bit of experience that every stone dealer | | | | ranged from bright and sunny to dark and |
| worth his rocks soon acquires is that a | | | | rainy. The purpose of these experiments was, |
| stone's appearance is not constant. Instead, | | | | of course, to see if the stones would change |
| it can and often does change with the quality | | | | at all in color appearance. |
| of light under which it is viewed. And a | | | | |
| change in color appearance often means a | | | | The gems were viewed four times daily. Hue, |
| change in value. | | | | lightness and saturation was recorded on each |
| | | | occasion, together with respective weather |
| In the days before electric light sources, | | | | conditions. These notations were based |
| traders could only view their prospective | | | | strictly on visual observation. No conclusive |
| purchases under natural light or by the light | | | | results were had, possibly because no |
| of a candle. Natural light means direct | | | | comparison reference was used; only the |
| sunlight and skylight (light coming from all | | | | testers' memories were involved, just like |
| directions of the sky except directly from | | | | with most dealers. |
| the sun). | | | | |
| | | | Now more curious than ever, the authors took |
| Some dealers would examine a stone at various | | | | a formal written survey of 20 colored-stone |
| times of the day, realizing that the position | | | | traders in order to compare their answers and |
| of the sun in the sky, together with weather | | | | see what patterns, if any, might emerge. |
| conditions, affected overall color | | | | |
| appearance; others took it one step further, | | | | The questions asked concerned the lighting |
| viewing the gem in sunlight, skylight and in | | | | conditions used for buying and selling, |
| the shade of a tree in order to get an idea | | | | whether rubies/blue sapphires change color |
| of how it would look in any lighting | | | | appearance at different times of the day (and |
| situation. Similar practices continue to this | | | | if so, when do they look best/worst) and |
| day, despite the availability of artificial | | | | specifically what factors are thought |
| lights of various kinds. | | | | responsible for color appearance changes when |
| | | | such changes are seen. |
| So, why examine gems under natural light, the | | | | |
| quality of which is subject to a myriad of | | | | All 20 traders were interviewed in Bangkok. |
| changing weather conditions, when our Modern | | | | They consisted of 9 Thais, 6 Americans, 3 |
| Age offers us incandescent and fluorescent | | | | Burmese, 1 Canadian and 1 Malaysian. The |
| (including simulated daylight) lighting? For | | | | majority are local wholesalers and sales |
| that matter, why bother to view a gem under | | | | personnel for local wholesalers. The others |
| more than one light source, be it natural | | | | consist of Thailand-based brokers and |
| outdoor light at a given time(s) of the day | | | | overseas-based dealers who buy in Thailand |
| vs. the stone's appearance in the shade, or | | | | and/or Sri Lanka and sell in Europe and/or |
| in fluorescent simulated daylight vs. | | | | America. The trade experience of those |
| incandescent lighting? The answers to those | | | | questioned ranged from 2 to 50 years, with |
| questions lie in whether you are an astute | | | | most having at least 10 years experience. |
| buyer or seller, and in what part of the | | | | Every attempt was made not to phrase |
| world you happen to be conducting business. | | | | questions in a leading way. People were |
| | | | simply asked questions and encouraged to |
| "One bit of experience that every stone | | | | "talk on" for as long as they wanted, without |
| dealer worth his rocks soon acquires is that | | | | prejudicing comments from the interviewer. |
| a stone's appearance is not constant. | | | | |
| Instead, it can and often does change with | | | | "All agreed that the color appearance of |
| the quality of light under which it is | | | | rubies and blue sapphires changes in the |
| viewed. And a change in color appearance | | | | course of a day, and all specified what times |
| often means a change in value." | | | | those stones look best/worst. But, to the |
| | | | authors' astonishment, there was no consensus |
| Viewing gems under natural light | | | | as to what those times are." |
| | | | |
| As in other parts of the world, it is common | | | | Survey results |
| practice in Thailand for dealers and | | | | |
| professional buyers to view colored stones at | | | | What lighting do you use when buying stones? |
| a table situated at a window. Natural light | | | | |
| is the accepted lighting "standard," some | | | | Most people (75%) said they buy ruby and |
| dealers and buyers preferring north skylight | | | | sapphire after examining those stones under |
| only. | | | | natural skylight only. Of those, seven people |
| | | | prefer north or northwest skylight, seven use |
| In the days before the GIA Diamondlite, such | | | | any direction of skylight, one specified |
| was also the case internationally with the | | | | north or south skylight and one south |
| color grading of diamonds. | | | | skylight only. Of the remaining 20%, one buys |
| | | | only after viewing each stone under north |
| Writing in 1916, Frank B. Wade notes in his | | | | skylight and direct sunlight; one uses north |
| classic volume on diamonds: | | | | skylight or a "daylight lamp"; two view their |
| | | | prospective purchases under multiple natural |
| "In the first place see that you have a good | | | | and artificial lighting conditions; one said |
| north light, unobstructed by buildings or | | | | he buys using "whatever lighting arrangement |
| other objects. There must not be any coloured | | | | happens to be available." |
| surface near by to reflect tinted light, as a | | | | |
| false estimate might easily result."In the | | | | Lighting used when selling stones? |
| second place, do not attempt to judge stones | | | | |
| at all closely except in the middle of the | | | | The majority (55%) of those questioned said |
| day, say between 10 A.M. and 2 P.M. Very | | | | they use skylight for selling as well as |
| erroneous results may easily be had by | | | | buying. Several stated categorically that the |
| neglecting this precaution."Dark or dull days | | | | color appearance of rubies and sapphires |
| should be avoided also. One must have plenty | | | | changes with the time of day and they |
| of good neutral light to make fine | | | | therefore prefer to buy in "bad light" and |
| comparisons." | | | | sell in "good light." The rational behind |
| | | | this is that if the stone appears reasonably |
| What Mr. Wade has to say about north light | | | | nice under less complimentary lighting, it |
| and (especially) weather conditions is echoed | | | | will look good under any (natural) lighting. |
| by many local colored-stone traders today. | | | | Selling in "good light" means exactly what it |
| However, the authors of this article were | | | | implies: during times when natural lighting |
| particularly struck by the comment "between | | | | conditions make the gem look best. |
| 10 A.M. and 2 P.M." as it is reminiscent of | | | | |
| remarks heard in Thailand and Burma about | | | | One dealer said he buys in Sri Lanka using |
| rubies and blue sapphires looking "better" or | | | | only northwest skylight, and sells in his |
| "worse" at different times of day. | | | | U.S. office under quartz halogen lighting. |
| | | | Another stated she buys rubies under north |
| So, wondered the authors, does the quality of | | | | skylight, but prefers selling them under |
| natural light vary enough to cause noticeable | | | | "direct sunlight in the afternoon, because |
| differences in the appearance of rubies and | | | | the light is yellow." In both instances, the |
| blue sapphires at different times? Not only | | | | lighting used for selling is perceived as |
| had Bangkok dealers mentioned this before, | | | | complimentary to the gem's color appearance. |
| but some had gone so far as to say that they | | | | |
| regulate their buying and selling according | | | | The rest largely buy in skylight and sell in |
| to the time of day and weather conditions. | | | | whatever lighting is available or under |
| | | | lighting conditions expressly requested by a |
| It was decided to telephone a few local | | | | customer, such as skylight from a particular |
| colored-stone dealers, all of whom have been | | | | window direction. Obviously, dealers who do |
| in the trade for years, and ask them the | | | | all their buying and selling from one office |
| following questions: | | | | location have more control over lighting |
| | | | conditions than does a broker who must sell - |
| Do rubies and/or blue sapphires change | | | | and accept consignments - under whatever |
| appearance at different times of the day?If | | | | lighting is available, natural or artificial. |
| yes, when do rubies look better/worse? When | | | | |