Gemstone Photography is a specialised field with a number of skills required to achieve consistent results. Some degree of gemmological knowledge is often required and understanding the basic principles of light and colour temperature is a real asset. Colour casts that interfere with a gem’s natural (intrinsic) hue or colour value is one of the first steps to master.
Photographic lighting techniques give rise to various colour temperatures which can interact with a gemstone’s unique light properties. Pleochroism for example; the property in which a gem appears more than one colour, many colours from different directions, or under fluctuating lighting conditions, can play havoc with the uninitiated photographer and resultant images.
Other properties like single or double refraction may further help or hinder results, or the degree by which a gemstone reflects or absorbs different spectral hues of the visible light spectrum. So it is often best to understand some optical properties of gemstones first and then go on to tackle accurate image colour and perfecting the medium of capture, which is largely digital in today’s photographic world. Digital camera sensors often see colours different to the naked eye.
It is also helpful to remember that certain gemstone varieties often embody the purest manifestation of colour in the physical world, which is part of their fascination and appeal. Blue sapphire for example can be found in some of the most fascinating and vibrant blues of the visible spectrum, from vivid indigos to rich royal blues or intense aqua or green-blue hues. This aspect of colour signatures and colour purity is also a key aspect of gemstone photography and why it is an invaluable subject medium for the budding photographer.
Tourmaline gems covering the blue and green hues of the colour spectrum
Gemstone photography is often best tackled in a step by step process. It is ideal to start with simple gemstone subjects like peridot or red garnets. Garnets are singly refractive, so you won’t have concerns about pleochroism or dichroism and they generally stay one colour from most lighting or viewing angles with flash lighting. They are often dark or deep red on account of their chemical make up which often causes a colour-subtractive or light absorbent effect. In this regard, you may often need a good deal more light going in than coming out with dark gems like garnets and some sapphires, than you would with say a ruby or the lighter spinel or tourmaline gems. Digital camera sensors also handle garnets well and generally produce a similar colour in camera as is seen to the naked eye. Try auto white balance on the cameras settings or experiment with neutral or warm white balance settings to see what gives the truest or most pure representation of the gems likeness.
By contrast, with peridot and many green gems, the camera’s sensor often captures greens slightly off hue. Lime green gems will often appear more yellow in camera so dedicated notes and colour grading systems are sometimes required. It is wise to develop your own colour grading or colour management system that works best with your particular lighting setup and processing, especially if you are working with raw files which can vary from camera to camera. Accurate colour capture involving a bit of experimentation along with descriptive details of colour and tonality being recorded is best, especially with expensive gems or gemstones which you may not get the chance to re-shoot.
First is is good to learn how different gem families such as Corundum, Spinel, Garnet or Tourmaline harness, reflect or absorb light. Then you are more prepared for capturing good images without too much frustration surrounding why you are not getting on camera what you see with the naked eye. This is because certain colours and light waves are preferentially absorbed, reflected or refracted within the matrix of the gem.