Abstract: A clasp according to an embodiment of the invention has a first annular body and a second annular body, the first annular body extending along an outer surface on one side of a semispherical portion of the spherical jewelry product, and the second annular body extending along an outer surface on the other side of the semispherical portion of the spherical jewelry product. In the case where two adjacent clasps are used so as to form a pair and in the case where the pair of clasps are closed, the shape of the proximal end of each of the first and second annular bodies is configured such that the proximal end in one clasp extends so as to pass through the inside of the other clasp and such that the proximal end in the other clasp extends so as to pass through the inside of one clasp.

Abstract: The present invention relates to a method for non-destructive judgment of pearl quality by measuring the ultraviolet-visible reflectance spectrum and/or ultraviolet-visible fluorescence spectrum of a pearl or pearl shell to be inspected and comparing the values obtained with those preliminarily measured for a normal pearl or pearl shell. The present invention also relates to a non-destructive inspection apparatus of pearl quality. According to the present invention, the quality of the aimed pearl or pearl shell can be easily and rapidly judged under a non-destructive condition.

Abstract: A clasp according to an embodiment of the invention has a first annular body and a second annular body, the first annular body extending along an outer surface on one side of a semispherical portion of the spherical jewelry product, and the second annular body extending along an outer surface on the other side of the semispherical portion of the spherical jewelry product. In the case where two adjacent clasps are used so as to form a pair and in the case where the pair of clasps are closed, the shape of the proximal end of each of the first and second annular bodies is configured such that the proximal end in one clasp extends so as to pass through the inside of the other clasp and such that the proximal end in the other clasp extends so as to pass through the inside of one clasp.