## 3 Results and Discussion
### DiamondView(tm) and Cathodoluminescence
It can be seen from the combination of the observation under DiamondViewTM and cathodoluminescence that, in the HTTP-treated diamond samples, the yellow-green samples presented yellow-green luminescence, while the yellow samples mainly presented luminescence characteristics of a combination of blue and green, and the brown and purple samples presented a luminescence of orange with different intensities. In the study of the cathodoluminescence of HTTP-treated diamonds, it has been proposed that the geometric luminous patterns of diamonds before and after HTTP treatment have obvious differences. On the [111] plane of natural brown-yellow diamonds without HTTP treatment, three groups of slip surfaces (lines) are generally developed. The slip band emits a more uniform strong yellow-green luminescence and obviously cuts through and destroys the primary growth ring structure of the diamond, while the locally remaining primary growth ring emits strong blue luminescence, and the sub-deformation transition zone emits uneven strong blue-white luminescence [10; 19]. However, HTTP conditions provide sufficient isotropic pressure and potential energy for the crystal defects in these brown and brown-yellow diamonds [10; 11]. On the basis of helping the crystal defects to change and achieve the purpose of color change, their luminosity will also be affected. The surface of a yellow-green diamond treated with HTTP shows strong yellow-green luminescence as a whole, and three groups of clear CL slip surfaces (lines) and CL  
Figure 3: Fluorescence images of samples under DiamondViewTM. deformation bands show strong yellow-green luminescence, which constitutes the characteristics of loading-type strong dislocation slip reflected in HTHP-treated yellow-green diamonds [10; 19]. [PERSON] and [PERSON] [20] combined HTHP-treated type Ia natural diamond fluorescence images and a PL spectrum analysis and found out that blue fluorescence is mainly caused by N3, while yellow-green fluorescence is related to an H3 center [5]. In addition, [PERSON] and [PERSON] [21] also proposed that HTHP-treated orange and yellow type Ia natural diamonds show orange-yellow fluorescence, mainly due to the presence of the 480 nm band. From the point of view of the luminous patterns, the samples appeared relatively complicated, and the luminous patterns were mainly divided into three types: regular annulus bands, multiple groups of intersecting linear stripes, and jagged stripes. [PERSON] and [PERSON] [22] studied the cathodoluminescence of the particulate diamond system in Yakut Kimberlite and concluded that there are three main types of diamond growth structure: single octahedral growth bands, complex growth bands, and multi-stage growth bands, and most diamonds are of the single octahedral growth band type. The regular growth bands observed in the samples here belong to this type of growth structure. According to [PERSON] et al. [23], these types of growth bands are straight with different widths and consist of non-luminescent regions and blue-green luminescence regions, arranged parallel from the center to the outside and obviously controlled by the layered growth mechanism. The three groups of fine linear textures observed in the samples are the characteristics of loading-type strong dislocation slip reflected in HTHP-treated diamonds. According to the study of [PERSON] [19], this is the important identification basis of HTHP-treated yellow-green diamonds. According to the study of [PERSON] et al. [24], the serrated ablation lines or irregular growth pattern and the dense growth pattern in the reaction stage indicate that the diamond grows under pulsating temperature-pressure conditions, and the pulsating characteristics reflect the periodic interaction between the fluid and the melt in an unstable state. Therefore, it can be inferred that the serrated growth texture in the samples observed under cathodoluminescence is an indication of its complex growth environment and process.