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There is a variety of stones and a variety of states for each particular stone during its polishing. Thus a model may have a different number of facets for the crown and pavilion and different positioning of them relative to each other. The HP Oxygen Carbon system aims to provide a universal approach allowing precise calculating of Girdle valley in all cases. It considers that zones for calculating the Girdle valley are always presented in spite of different facet sets of a crown and pavilion. The wide-facet term is used to define those zones. The wide-facet is a facet on crown or pavilion that could be any type: main facets, upper, lower facets and any other, if it has the longest width in a place where it touches girdle (marked as yellow on the picture below). Usually, the upper and lower girdle facets are wide-facets. Main facets could be wide-facets in semi-polished diamonds, while upper and lower girdle facets are not made yet.

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The difference between  Pavilion heights valley  and  Pavilion height valley type 2  are shown on the picture below. Left picture illustrates measurements of  Pavilion heights valley , by first method (blue arrows), and right picture illustrates measurements of  Pavilion heights valley type 2 , by second method (green arrows).  Crown height valley  are shown by black arrows. The Pavilion height valley type 2 parameter is used not to lose measurements are shown on the right picture.

Previous Versions

HP Oxygen Carbon is an inheritor of the HP Pacor in many aspects including the approach to how stone heights are calculated.

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