A system comprising: a sensing cell comprising: a walled structure configured to receive a fuel sample within an interior space of the walled structure; at least one cooling surface located on at least a portion of the walled structure and configured to cool the fuel sample; a first optical port positioned on a first wall of the walled structure, the first optical port configured to be coupled to at least one optical fiber and to provide first radiation to the fuel sample; a mirror positioned on a second wall of the wall structure opposite from the first wall, the mirror configured to reflect the first radiation in order to provide second radiation to the first optical port; characterised in that a second optical port positioned on the first wall adjacent to the first optical port, the second optical port configured to receive third radiation reflected by the mirror for diffuse measurements for the fuel sample; wherein the first optical port defines a collinear optical geometry for providing the first radiation to the fuel sample and receiving the second radiation through the fuel sample; at least one cooler configured to cool the fuel sample in the sensing cell by cooling the at least one cooling surface to cause wax particles to form in the fuel sample; at least one heater configured to warm the fuel sample in the sensing cell to cause the wax particles in the fuel sample to melt; and an analyzer configured to analyze at least one of the second radiation and the third radiation to identify at least one of a cloud point of the fuel sample and a freeze point of the fuel sample. a sensing cell comprising: a walled structure configured to receive a fuel sample within an interior space of the walled structure; at least one cooling surface located on at least a portion of the walled structure and configured to cool the fuel sample; a first optical port positioned on a first wall of the walled structure, the first optical port configured to be coupled to at least one optical fiber and to provide first radiation to the fuel sample; a mirror positioned on a second wall of the wall structure opposite from the first wall, the mirror configured to reflect the first radiation in order to provide second radiation to the first optical port; characterised in that a second optical port positioned on the first wall adjacent to the first optical port, the second optical port configured to receive third radiation reflected by the mirror for diffuse measurements for the fuel sample; wherein the first optical port defines a collinear optical geometry for providing the first radiation to the fuel sample and receiving the second radiation through the fuel sample; a walled structure configured to receive a fuel sample within an interior space of the walled structure; at least one cooling surface located on at least a portion of the walled structure and configured to cool the fuel sample; a first optical port positioned on a first wall of the walled structure, the first optical port configured to be coupled to at least one optical fiber and to provide first radiation to the fuel sample; a mirror positioned on a second wall of the wall structure opposite from the first wall, the mirror configured to reflect the first radiation in order to provide second radiation to the first optical port; characterised in that a second optical port positioned on the first wall adjacent to the first optical port, the second optical port configured to receive third radiation reflected by the mirror for diffuse measurements for the fuel sample; wherein the first optical port defines a collinear optical geometry for providing the first radiation to the fuel sample and receiving the second radiation through the fuel sample; at least one cooler configured to cool the fuel sample in the sensing cell by cooling the at least one cooling surface to cause wax particles to form in the fuel sample; at least one heater configured to warm the fuel sample in the sensing cell to cause the wax particles in the fuel sample to melt; and an analyzer configured to analyze at least one of the second radiation and the third radiation to identify at least one of a cloud point of the fuel sample and a freeze point of the fuel sample.