172 



graphic uiul optical tests show tliat the material submitted is crystallized 

 ai'd that the coue by all tests is one homogeneous faceless (auhedral) 

 crystal. The crystalline, optical and other characteristics determined are 

 closely those of natural sapphire. In the absence of natural faces or 

 cleavages the crystalline system, as determined by the optical tests, may 

 be either hexagonal or tetragonal. The parting figures point to the hexa- 

 gonal system. Any two natural substances which were as nearly identical 

 in chemical and crystallographi< characters as the si>ecimens submitted 

 and natural sa]>iihires would Ik cillcd identical. The difference is one 

 of origin "' 



While expert mim'ralnglsts arc agreed that tliese synthetic products 

 are identical with the natural in all their proi)erties. yet the synthetic 

 stones may in nearly every case be distinguished from the natural by one 

 wlio is trained in seeking niinnle ditTei'eiiccs due to the difference in origin. 

 As is now well known in the trade, the synthetic stones freciuently contain 

 bubbles which are always round or rounding in form. Natural corundum 

 gems also fi-equcnt|y contain bnlilihs. liut these are always bounded by 

 crystal planes and are hence angular in ai)pearance. Lacking the bubbles 

 stri;e may be schmi in the synthetic stones. esi.ie<-ially in the rubies, and 

 these stria', while jiarallcl like those so often seen in n.ituial stones, are, 

 uidike the latter, not straight but curving. The color, too, in the case of 

 the ruby, is not ipiite equal to that of the best natural stones, although 

 in this respect I hoi)e to show that the delect is probably due to improper 

 cutting rather than to any r".il <liflerence in the material. The synthetic 

 rubies seem also to interfere with the p;is«age of light through them to a 

 greater extent than the natural stones wlien the latter are clear. This 

 result'^ in a sort of general illumination of the interior of the stone. One 

 might say that the material was not optically a vacuum and that the 

 Tyndall effect was produced. The flashes of light produced by total re- 

 flection from the rear facets of the stone are therefore seen against a 

 background of faintly illuminated niat''ri:il instead of against a dark 

 background, as in the natural ruby. Thi< detracts from the beauty of 



the synthetic ruby s ewhat. and it is this jilienonienon I believe which 



enables an exijert t(» tel! by inspection without the aid of a lens whether 

 a stone is a natural or .i synthetic ruhv. Some exjierts have claimed that 

 they could tell by the touch alone whether a stone was a synthetic or a 

 natural one. This difference I believe to be due to the very hasty manner 



