Abstract:
The invention is a multicolored reflecting disc that can be mounted to a lens for grading gemstone brightness and symmetry. The disc has an opening or aperture through which the gemstone is viewed on the object side of the lens. The aperture is surrounded by multicolored concentric rings which face the gemstone. Light reflecting from the multicolored rings creates specific colors on the gemstone that allow symmetry and brightness of the tone to be evaluated.

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to a device for observing and analyzing the quality of precious stones, especially diamonds, and in particular to a device which provides relevant information regarding a stone&#39;s symmetry, brightness, and efficiency of light return. 
     BACKGROUND OF THE INVENTION 
     While a significant part of a diamond&#39;s value is determined by its weight or carat, the popularity of diamonds as gem stones is due in large part to their inestimable brilliance. The degree of a diamond&#39;s brilliance is influenced significantly by its cut, transparency, clarity, and color. 
     When diamonds are cut to traditional “ideal” cut angles and the facets are carefully aligned to facilitate “mirroring,” light leakage can be minimized and a greater percentage of light will be returned to the viewer, thereby giving the diamond a brighter appearance. “Mirroring” refers to the reflection of light to form symmetrical geometric patterns, wherein the facets work together to collect light and return the maximum amount of light to the viewer. 
     Brightness, however, is a function of several attributes of cutting. Even though light may not be “leaking” or passing through the rear side (“pavilion”) of the diamond, there is no guarantee that large amounts of light are being returned to the viewer. In order to evaluate the efficiency of light return, light must be gathered from around the viewer, and its reflective pattern analyzed. 
     Heretofore invented has been a device (see U.S. Pat. No. 4,647,194) which relates to the judging of brilliancy in diamonds by viewing a stone through a magnifying lens wherein the object side of the lens is fitted with a solid red colored disc having a centrally-located hole. Viewing the diamond through the lens assembly provides the viewer with an image of the diamond in which those areas which are reflecting light to the viewer appear as red, whereas those areas of the diamond not reflecting light, but leaking light through the pavilion, appear colorless. This observation allows the viewer to form a general conclusion about the light reflective properties or brilliancy of the particular stone. 
     The prior art device does not, however, permit the angles of reflective light to be analyzed. Consequently, no information is available regarding the stone&#39;s symmetry or the efficiency of light return based on the cut of the diamond. Without such information, faults in the diamond&#39;s cut may not be apparent, particularly to an inexperienced purchaser. Such faults may significantly impact the appearance of the gem stone and detract from its total value. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to address the aforementioned problem and provide a device with which a viewer may judge a stone&#39;s brightness and symmetry via the observed efficiency of light return from various angles of incidence upon the diamond. 
     The device of the present invention comprises a simple body wherein a precious stone such as a diamond is placed between a light source and a magnifying lens. The lens is equipped, on the object side, with a multicolored disc wherein each color represents a ring around a portion of the disc, and wherein the stone is viewed through a centrally-located hole in said disc. 
     Light from the light source is reflected from each colored ring onto the diamond&#39;s surface at an angle defined by the ring&#39;s position from the center of the disc through which the observer views the diamond. Because each angle or range of angles is represented by a specific color, light return efficiency can be analyzed and the symmetry and brightness of the stone evaluated. 
    
    
     Other objects, advantages, and features of the present invention will be apparent to the reader from the foregoing and the appended claims, and as the ensuing detailed description and discussion of the invention proceeds in conjunction with the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings, like reference numerals refer to like parts throughout the various views unless indicated otherwise, and wherein: 
     FIG. 1 is a bottom plan view of a lens bracket embodying the principles of the present invention; 
     FIG. 1A is a perspective view of a multicolored reflecting disc; 
     FIG. 2 is a side elevational view of the lens bracket illustrated in FIG. 1; 
     FIG. 3 is a front perspective view of a viewing device which may incorporate the principles of the present invention; 
     FIG. 4 is a side perspective view of the device illustrated in FIG. 3; 
     FIG. 5 illustrates the image of an observed diamond with the red portion of the image shown separately; 
     FIG. 6, like FIG. 5, illustrates the image of an observed diamond with the green portion of the image shown separately; 
     FIG. 7, like FIGS. 5 and 6, illustrates the image of an observed diamond with the dark blue portion of the image shown separately; 
     FIG. 8, like FIGS. 5-7, illustrates the image of an observed diamond with the black portion of the image shown separately; 
     FIG. 9 illustrates the image of an observed diamond that is substantially symmetrical; and 
     FIG. 10 illustrates the image of an observed diamond that is less symmetrical than the diamond illustrated in FIG.  9 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, FIG. 1 illustrates the underside of a lens bracket generally at  10 . Colored rings  12 ,  14 ,  16 , and  18  are fixedly secured to the surface of a disc  20  (see FIG. 1A) via an adhesive or other appropriate method. Disc  20  is a cylinder, open at one end  22 , and capable of being fitted and frictionally secured to the object side of a magnifying lens  30  (see FIGS. 3,  4 ). 
     The colors respectively associated with each ring of the disc  20  are irrelevant, but should be chosen to easily permit the observer to distinguish between the various colors since each color represents a distinct range of angles from which light is incident upon the top surface (“table”) of the diamond. In the present embodiment used for illustrative purposes herein, each ring is associated with the following color: Ring  12  is red; ring  14  is green; ring  16  is dark blue; and ring  18  is light blue. Circular recess  24  and longitudinally extending slot  26  of lens bracket  10  are also colored similarly to the outermost ring  18 , in this case light blue. The remaining portion  28  of the underside of lens bracket  10  is outside the critical angle and is not reflected to the overhead viewer by the diamond. This portion of the lens bracket is black in color. It should be noted that the overhead viewer may in fact observe a black reflection from the diamond as illustrated in FIG.  8 . This black portion of the image is formed by reflected light that entered the diamond from 90 to 75 degrees to the table and generally represents the image of the overhead viewer as he or she observes the diamond through magnifying lens  30 . 
     Referring now primarily to FIGS. 2-4, lens bracket  10  is mounted between a first grooved side wall  32  and a second grooved side wall  34 . Lens bracket  10  is secured between first and second grooved side walls  32 ,  34  by extending pins  36  which are received in spaced openings (not shown) machined into the inner surfaces  38 ,  39  of grooved side walls  32 ,  34 . Grooves  40 ,  42  extend longitudinally along the inner surfaces  38 , 39  of grooved side walls  32 , 34  to receive sliding plate  44 . 
     A row of conical depressions (not shown) machined into the surface of sliding plate  44  support diamonds of various sizes and permit the user to position a particular stone directly below magnifying lens  30  for observation. After the selected diamond has been positioned below magnifying lens  30 , the user activates the light source located below the diamond and sliding plate  44 , and can then evaluate the symmetry, brightness, and sufficiency of light return for the particular stone. 
     Turning now to FIGS. 5-8, the image of a substantially symmetrical diamond  46  is illustrated in association with the separate image of a portion of the light reflected to the overhead viewer. The multicolored image of the substantially symmetrical diamond  46  is a composite of light incident upon the crown of the diamond from all angles greater than the critical angle. This image is that which is observed by the overhead viewer. In correspondence with the illustrative selected colors set forth above, FIG. 5 illustrates the red portion of the image  48  which is that light that is incident upon the crown of the diamond from 75 to 65 degrees and then reflected directly to the overhead viewer. FIG. 6 illustrates the green portion of the image  50  which is that light that is incident upon the crown of the diamond from 65 to 55 degrees and then reflected directly to the overhead viewer. FIG. 7 illustrates the dark blue portion of the image  52  which is that light that is incident upon the crown of the diamond from 55 to 45 degrees and then reflected directly to the overhead viewer. FIG. 8 illustrates the black portion of the image  54  which is that light that is incident upon the crown of the diamond from 90 to 75 degrees and then reflected directly to the overhead viewer. The remainder of the composite image  46  consists of light blue portions representing light incident upon the crown of the diamond at less than 45 degrees, but greater than the critical angle. 
     FIG. 9 is a larger image of the multicolored composite image illustrated at  46  in FIGS. 5-8 demonstrating the symmetrical nature of the particular gemstone viewed through magnifying lens  30 . FIG. 10 illustrates the multicolored composite image  56  of a less symmetrical diamond as viewed under the same conditions through the magnifying lens. The erratic table reflections shown in this image illustrate the lack of symmetry in this particular gemstone. Such erratic reflections limit the brilliance of the stone and may detract from its overall value. 
     The multicolored rings  12 ,  14 ,  16 , and  18  define at least two differently colored areas on the disc surface  20  facing away from the lens  30  and toward the gemstone. While it is believed that the concentric, multicolor ring arrangement described above is preferred, it may be possible to accomplish the same function by simply using different colored surface areas that have another geometric arrangement. Therefore, while the invention is described and illustrated here in the context of diamonds, and with particular color selections for the rings of the multicolored disc, the invention may be embodied in many forms without departing from the spirit or essential characteristics of the invention. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive. The scope of the invention is indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.