A pearl grading method includes the following steps: (1) determining the color type of the pearl to be graded; (2) generating a simulated three-dimensional graph of the pearl to be graded; (3) calculating roundness, so as to obtain a roundness grade; (4) calculating the diameter of the simulated three-dimensional graph, so as to obtain a diameter grade; (5) drawing an illumination-wavelength reflection spectrum; (6) changing a detected part, and drawing an illumination-wavelength reflection spectrum again; (7) repeating the step (6) for at least two times; (8) performing weighted average to obtain a correction curve; and (9) comparing the correction curve with each glossiness grade spectrum baseline, so as to determine a glossiness grade according to the spectrum baseline with the highest coincidence degree. The method has the beneficial effects of low cost, high speed, good result consistency and high detection precision.

A microstrip-type microwave sensor for the measurement of the dielectric properties of a solid or liquid material, constituted by a main line and two connected transmission lines integral at one of their extremities to the main line, the main line and two connected transmission lines being spaced from one another by a slot and being made integral with a substrate. The main line is connected to an electrical circuit by each of its two extremities to inject a sinusoidal signal, and wherein said main line has a width giving it an impedance in the range 50 Ohm, the two connected transmission lines being of the same width and of a length equal to one quarter of the wavelength guided in the substrate, the substrate having a height or thickness giving it flexibility or rigidity, the substrate being applied to a metallic support formed of a layer of metallic material.

Systems and methods here may be used for a setup of image capturing of a gemstone, such as a diamond, exposed to different light sources. Some examples utilize a setup that both sends light and captures the image through multiple dichroic beam splitters at pre-selected timing. The multiple light source and multiple dichroic beam splitter arrangement allows for multiple gemstones to be analyzed using multiple methods with minimal moving, changing, or adjusting the equipment for different samples.

A device for inspection and authentication of gemstones (diamond pieces) includes a first member having a plurality of gemstone receiving portions, a second member having a plurality of diamonds covering portions which correspond to the gemstone receiving portions; each of the diamond covering portions having a viewing and inspection opening formed therein, a connection member disposed between end portions of the first and second members, a seal placement area formed on each of the first and second members; and an authentication seal configured to be placed on the seal placement area. The authentication seal is provided on the seal placement area without obstructing the viewing and inspection openings. The size of the viewing and inspection openings is less than size of gemstones placed in the gemstone receiving portion. The viewing and inspection opening includes one or more elongated portions for inserting a twizzer therethrough for holding and rotating diamond.

Provided herein is an apparatus for assessing a color characteristic of a gemstone. The apparatus comprises an optically opaque platform for supporting a sample gemstone to be assessed, a daylight-approximating light source to provide uniform illumination to the gemstone, an image capturing component, and a telecentric lens positioned to provide an image of the illuminated gemstone to the image capturing component. Also provided are methods of color analysis based on images collected using such an apparatus.

Gemstone grading method including illuminating the gemstone by light having a plurality of spectral components, each modulated according to a spectrally specific modulation (e.g., of intensity, frequency, phase), collecting the light following interaction with the gemstone, extracting from the collected light a set of intensity values for a respective set of modulation parameter values to provide a transmittance spectrum, and an output indicative of the transmittance spectrum (e.g., color, clarity, fluorescence grade). A complementary system includes a plurality of monochromatic light sources and respective modulators for simultaneously illuminating a gemstone with a modulation spectrally specific for each light source, a detection system for collecting the light following interaction whose signals are fed via a communication system to a data processor configured to extract a set of intensity values for a respective set of modulation parameter values to provide a transmittance spectrum and an output indicative thereof.

A system for the automatic grading of a cut/polished gemstone (SUT) includes an enclosure with a stage for mounting the cut/polished SUT. The enclosure further includes one or more sources of broadband visible (BBV) light, the sources of BBV light being controllable by a programmable controller; an image sensor for capturing a plurality of images of a mounted SUT, and one or more sources of UV light mounted within the enclosure. The controller captures images of the mounted SUT from one or more selected angles relative to the sensor elevation axis and relative to the position of the SUT on the stage rotation axis; an image capturing module is configured for processing the one or more images; and, a light grade calculation module is configured for grading the cut/polished SUT using light indicative parameters from at least a part of the one or more images captured.

Method and systems are presented for authentication of precious stones, according to their natural ID and/or predetermined markings created in the stones, based on unique characteristic radiation response of the stone to predetermined primary radiation.

A multi-functional precious stone testing apparatus includes a portable housing and a testing unit. The portable housing includes a portable housing having a hand-held casing and a probe casing extended from a front end of the hand-held casing. The testing unit housed in the hand-held casing includes a UV light emission unit, a UV light reflecting and guiding unit, and a UV light receiving unit. The UV light emission unit produces and emits both a long-wave UV light and a short-wave light, so as to allow the UV receiving unit to sense the UV lights reflected and refracted by a testing object for determining various qualities and distinguishing types of diamond of the testing object.

Methods, apparatus, and systems for managing optical characteristics of gemstones with diffractive structures are provided. In one aspect, a method includes obtaining a three-dimensional model of a gemstone including representations of surfaces of the gemstone, identifying a region on a surface of the gemstone having an optical value higher than one or more other regions on the surface of the gemstone by analyzing the three-dimensional model of the gemstone, and determining a diffractive structure to be arranged on the identified region of the surface of the gemstone, such that the gemstone with the diffractive structure has a higher optical performance than the gemstone without the diffractive structure. The method can also include fabricating the determined diffractive structure on the identified region of the surface of the gemstone.