A method for screening a gemstone based on its fluorescence emission, comprising: applying radiation at a pre-set excitation wavelength of 385 nm to a gemstone by placing a fiber optic probe near or touching the gemstone, wherein the radiation is rendered by coupling an LED light source with a first lens (#1) configured to collimate light from the LED light source, wherein the first lens is positioned at a first back focal length from the LED light source, coupling the first lens with a short pass filter, and coupling the short pass filter with a second lens (#2) configured to collect light to send through the fiber optic probe that is connected to a first fiber port, wherein the first fiber port is positioned at a second back focal length from the second lens, and wherein the short pass filter is set at a first predetermined wavelength of 390 nm; receiving, using the fiber optic probe, fluorescence emission from the gemstone; receiving, at a fluorescence detector, modified fluorescence emission from the gemstone, wherein the modified fluorescence emission is rendered by coupling the fluorescence detector with a first fluorescence lens (#4), coupling the first fluorescence lens with a long pass filter, and coupling the long pass filter with a second fluorescence lens (#3), wherein the second fluorescence lens is positioned at a third back focal length from a second fiber port, wherein the first fluorescence lens is placed at a distance which is at a fourth back focal length from the fluorescence detector, and wherein the long pass filter has a second predetermined wavelength of 409 nm; and automatically collecting and analyzing, by a computing device with a processor and memory and in communication with the fluorescence detector, one or more measurements of the modified fluorescence emission, wherein: if the modified fluorescence emission is a modified fluorescence emission pattern of a natural gemstone, a positive testing result is displayed with sound notification, and if the modified fluorescence emission is not a modified fluorescence emission pattern of a natural gemstone, a non-positive testing result is displayed with sound notification, indicating the gemstone to be referred for further testing. applying radiation at a pre-set excitation wavelength of 385 nm to a gemstone by placing a fiber optic probe near or touching the gemstone, wherein the radiation is rendered by coupling an LED light source with a first lens (#1) configured to collimate light from the LED light source, wherein the first lens is positioned at a first back focal length from the LED light source, coupling the first lens with a short pass filter, and coupling the short pass filter with a second lens (#2) configured to collect light to send through the fiber optic probe that is connected to a first fiber port, wherein the first fiber port is positioned at a second back focal length from the second lens, and wherein the short pass filter is set at a first predetermined wavelength of 390 nm; receiving, using the fiber optic probe, fluorescence emission from the gemstone; receiving, at a fluorescence detector, modified fluorescence emission from the gemstone, wherein the modified fluorescence emission is rendered by coupling the fluorescence detector with a first fluorescence lens (#4), coupling the first fluorescence lens with a long pass filter, and coupling the long pass filter with a second fluorescence lens (#3), wherein the second fluorescence lens is positioned at a third back focal length from a second fiber port, wherein the first fluorescence lens is placed at a distance which is at a fourth back focal length from the fluorescence detector, and wherein the long pass filter has a second predetermined wavelength of 409 nm; and automatically collecting and analyzing, by a computing device with a processor and memory and in communication with the fluorescence detector, one or more measurements of the modified fluorescence emission, wherein: if the modified fluorescence emission is a modified fluorescence emission pattern of a natural gemstone, a positive testing result is displayed with sound notification, and if the modified fluorescence emission is not a modified fluorescence emission pattern of a natural gemstone, a non-positive testing result is displayed with sound notification, indicating the gemstone to be referred for further testing. if the modified fluorescence emission is a modified fluorescence emission pattern of a natural gemstone, a positive testing result is displayed with sound notification, and if the modified fluorescence emission is not a modified fluorescence emission pattern of a natural gemstone, a non-positive testing result is displayed with sound notification, indicating the gemstone to be referred for further testing.