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It is important to correlate the properties of a specimen in research on the real structure of diamonds. We have shown [1,2] that the extra reflections of thorn shape in Laue patterns are quantitatively related to the 1365 cm -~ IR band. It has now been found that these reflections for natural diamonds are due to platelets parallel to the cube faces, whose existence was predicted theoretically in a discussion of the nature of the reflections [3]. These platelets were subsequently observed directly with the electron microscope [4].It has become generally accepted in the literature on diamonds that these platelets contain most of the nitrogen impurity, which if present in high concentration gives rise [5] to the main features of the IR and UV spectra of type I diamonds.* This follows from a study [8] of the parallel trend in the strength of these extra reflections and the UV absorption. We have shown [1, 2] that ~trogen Which produces the A bands in the IR (strongest band 1282 em -1) and the UV absorption below 3000 A has no relation to the extra reflections, and hence to the platelets; it is present in some other form, perhaps as N 2 groups.~ The nature of the platelets thus remains open.One way of resolving this problem is to examine how these structure defects affect the physical properties of diamonds. We have examined the effects of platelets on the UV absorption spectrum and on the *Gas chromatography [6] and activation analysis [7] show that type I diamonds contain much nitrogen. t This, however, does not rule out presence of some of the nitrogen in platelet form.

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