Optics: measuring and testing – Crystal or gem examination
Reexamination Certificate
2000-08-31
2004-09-21
Font, Frank G. (Department: 2877)
Optics: measuring and testing
Crystal or gem examination
Reexamination Certificate
active
06795171
ABSTRACT:
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's symmetry, brightness, and efficiency of light return.
BACKGROUND OF THE INVENTION
While a significant part of a diamond'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'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.
A variety of devices have been invented for judging the brilliancy of diamonds. One such device, described in U.S. Pat. No. 4,647,194, 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.
An additional device, described in U.S. Pat. No. 5,260,763, permits a user to observe a diamond through a magnifying lens positioned over or near the end of a tubular device with the diamond or other gemstone located at the opposite end. Light reflecting from the cylindrical interior of the tube creates a pattern on the surface of the gemstone that is ultimately reflected to the overhead viewer. This instrument employs a solid-colored surface such as red or silver to form reflective patterns on the gemstone so that an observer may form a general conclusion regarding the light reflective properties or brilliancy of the particular stone being observed.
The prior art devices are limited in their ability to produce an image which permits the angles of reflective light to be analyzed. Consequently, no information is available regarding the stone's symmetry or the efficiency of light return based on the cut of the diamond, or other gemstone. Without such information, faults in a gemstone'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's brightness and symmetry via the observed efficiency of light return from various angles of incidence upon a diamond or other gemstone. The device embodied by the present invention is an improvement over prior art devices in that the reflective surface incorporates two or more distinctive colors arranged in a pattern which, when reflected from the surface of a gemstone to an overhead viewer, produces an image of a color pattern on the gemstone representative of the gemstone's symmetry.
An embodiment 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. The multicolored disc may also incorporate color patterns other than rings which provide information about the symmetry of a gemstone or parts thereof.
Light from a light source is reflected from each colored ring onto the diamnond's surface at an angle defined by the ring'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.
In an alternate embodiment of the invention, the multicolored reflective surface takes the form of a cylinder through which a gemstone such as a diamond is viewed. Observation of a gemstone positioned at or near one end of the cylindrical multicolored surface is facilitated by a magnifying lens positioned at or near the opposite end of the cylindrical reflective surface.
An additional objective of the present invention is to provide a means of photographing gemstones and their reflective symmetry patterns by incorporating a camera in place of the magnifying lens described above in an embodiment made to facilitate such photography.
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.
REFERENCES:
patent: 4647194 (1987-03-01), Shigetomi et al.
patent: 5196966 (1993-03-01), Yamashita
patent: 5260763 (1993-11-01), Yamashita
patent: 5430538 (1995-07-01), Kobayashi
patent: 6348964 (2002-02-01), Wagner et al.
patent: 6665058 (2003-12-01), Gilbertson
EightStar Diamond Company, Inc.
Font Frank G.
Lauchman Layla
Miller Nash LLP
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