A method of characterising a composition of a gemstone comprises irradiating an upper portion and a lower portion of the gemstone with one or more pulses of ultraviolet radiation at a wavelength of substantially 225 nm or less; capturing luminescence emitted by the upper portion of the gemstone and luminescence emitted by the lower portion of the gemstone in one or more time windows having a predetermined relationship with the or each pulse; and comparing properties of the captured luminescence from the upper and lower portions. A composition of the gemstone is characterised, based upon the comparison.

A method of determining the composition of a polished gemstone comprises passing an excitation beam through the gemstone from a table facet substantially to a culet of the gemstone, an axis of the excitation beam being substantially perpendicular to the table facet; and capturing luminescence emitted by the gemstone from an angle oblique to the axis of the excitation beam.

A method of determining the composition of a polished gemstone comprises passing an excitation beam through the gemstone from a table facet substantially to a culet of the gemstone, an axis of the excitation beam being substantially perpendicular to the table facet; and capturing luminescence emitted by the gemstone from an angle oblique to the axis of the excitation beam.

A computer-based system and method for taking clarity measurements of a gem, and a computer-readable medium having computer-executable instructions, are provided and include receiving a pixilated image of a gem and identifying pixels representing an inclusion. The method and medium further include determining characteristics of the inclusion as a function of the pixels representing the inclusion, and providing a clarity grade based upon the determined characteristics. Also provided is a method for mapping a gem, and a computer-readable medium having computer-executable instructions, which include receiving a pixilated image of a gem having facet edges, and identifying pixels representing the facet edges. The method and medium further include generating a diagram of the gem, such that the diagram is a function of the pixels representing the facet edges, and superimposing the diagram onto the pixilated image.

A computer-based system and method for taking clarity measurements of a gem, and a computer-readable medium having computer-executable instructions, are provided and include receiving a pixilated image of a gem and identifying pixels representing an inclusion. The method and medium further include determining characteristics of the inclusion as a function of the pixels representing the inclusion, and providing a clarity grade based upon the determined characteristics. Also provided is a method for mapping a gem, and a computer-readable medium having computer-executable instructions, which include receiving a pixilated image of a gem having facet edges, and identifying pixels representing the facet edges. The method and medium further include generating a diagram of the gem, such that the diagram is a function of the pixels representing the facet edges, and superimposing the diagram onto the pixilated image.

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

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

There is provided a computerized system and method of generating a unique identification associated with a gemstone, usable for unique identification of the gemstone. The method comprises: obtaining one or more images of the gemstone, the one or more images captured at one or more viewing angles relative to the gemstone and to a light pattern, thus giving rise to a representative group of images; processing the representative group of images to generate a set of rotation-invariant values informative of rotational cross-correlation relationship characterizing the images in the representative group; and using the generated set of rotation-invariant values to generate a unique identification associated with the gemstone. The unique identification associated with the gemstone can be further compared with an independently generated unique identification associated with the gemstone in question, or with a class-indicative unique identification.

There is provided a computerized system and method of generating a unique identification associated with a gemstone, usable for unique identification of the gemstone. The method comprises: obtaining one or more images of the gemstone, the one or more images captured at one or more viewing angles relative to the gemstone and to a light pattern, thus giving rise to a representative group of images; processing the representative group of images to generate a set of rotation-invariant values informative of rotational cross-correlation relationship characterizing the images in the representative group; and using the generated set of rotation-invariant values to generate a unique identification associated with the gemstone. The unique identification associated with the gemstone can be further compared with an independently generated unique identification associated with the gemstone in question, or with a class-indicative unique identification.

There is disclosed an apparatus and method for sorting gemstones from a batch of gemstones. The apparatus comprises one or more measurement locations, each comprising at least one measurement device configured to measure one or more properties of a gemstone. A continuously moveable surface supports the gemstones thereon and transports the gemstones to the one or more measurement locations. A separation device separates the gemstones from one another as they are transported on the moveable surface to the one or more measurement locations. A location trigger at a sensor location comprises a sensor for identifying when the gemstone passes through the sensor location. A controller receives a signal from the location trigger, records the position of the moveable surface when the signal is received, and tracks the subsequent location of the gemstone by monitoring the movement of the moveable surface such that a measurement of the one or more properties of each gemstone can be correlated with a location of the respective gemstone on the moveable surface. Specific markers in the luminescence properties of the gemstone may be used to identify properties of the stone.