Crystals can be changed by man in various ways. Polishing and tumbling stones in a machine or by hand smooths crystal edges and makes them shine. Lapidary work and faceting makes crystals reflect more light. Often crystals can be carved into different figures such as angels, egg/ball shapes or animals. Colours of crystals can be changed by artificially heating or dying a stone.
Man can also imitate crystals using different methods. Colour manipulation can be achieved with dyes (like howlite dyed blue for turquoise or lightening pearls using bleach), or “impregnation” process (for example injecting plastic into common opal for a play on colours or mixing wax/silica with turquoise for colour stabilisation), or treating with sugar solutions/acid. Other materials can be used to create stones (for example, zircon metals used to imitate diamonds, haemalin is artificial hematite made of stainless steel, goldstone is manufactured glass with particles of copper, soude emeralds are layers of green glass and quartz). Some crystals (like diamonds, rubies and sapphires) can be synthetically made.
There can be advantages and disadvantages to using treated crystals. Imitation stones can be misleading, making it confusing to identify or choose the correct crystals and people may end up paying more for a cheap stone. Using artificial materials and methods to changed crystals could disturb the stone’s natural vibrations. Changing the size of crystals makes them more practical to use in healing and meditation (for example a small, smoothed tumbled stone may be more safer to use than a heavy cluster with sharp points). Altering the shape of a crystal can give a person more focus during their meditations (spheres used for scrying or wands for seeking direction) or could enhance the stone’s energy (such as angel figures carved from rose quartz to promote love and healing). Faceted stones can be made into jewellery which allows the wearer to have a crystal close to them for a consistent time (like a carnelian belt buckle for base chakra or turquoise necklace for throat chakra or a citrine navel ring).
I sometimes use shaped crystals in my Magikal practices as I find the figure of a stone can enhance the magical properties of a spell/ritual by give more focus to a particular thought form (like a piece of pyrite in a coin shape to attract prosperity or aquamarine carved to look like a dolphin to represent the element of Water). I prefer using small tumbled stones in healing crystal layouts as they are easier to place on the body, safer to use and easier to transport/store away. I would use bigger clusters of crystals for larger areas around the home and smaller clusters for aura combing. I favour naturally created stones to artificially made crystals for healing and meditation as I believe the healing vibrations of natural stones give a more pure, “free range”, organic energy.