The difference between sapphire, glass and crystal
Sapphire is a term that is often misused. Watch-makers sometimes use the words sapphire, glass or crystal to designate the cover that protects the dials of their watches, but they can be made of mineral glass (regular glass that can break and scratch relatively easily) or of sapphire crystal (a man-made sapphire crystal which has the same properties as its natural cousin found in the earth). Sapphire crystal distinguishes itself by its hardness (second only to the diamond), its strength, lightness and resistance to scratches. (See our articles on watch crystals and Century) .
Crystals used in jewellery and watch decoration, on the other hand, are produced using micro-electronic and mechanical technology and contain large quantities of lead oxide to increase the refraction of light and better allow cutting and engraving, although they are not as strong or scratch resistant as sapphire crystal and are far easier to craft and manipulate.
Century makes all of its watchcases out of the finest sapphire crystal. It takes several days for the brand’s master craftsmen and women to completely cut and polish one crystal. “From a chemical, physical and crystallographic point of view, Century sapphire has the same identity, the same property and even the same structure as natural sapphire,” explains Nathalie Kotellat, Century’s Director for Communications. “It can only be worked with diamond tipped tools and diamond powder, which is very costly,” she continues. Every facet of Century crystal is cut and polished by hand in a traditional fashion, which brings extra special added value to watch cases crafted out of Century sapphire.
The Century process
Each Century crystal bezel and case design is created according to pre-defined and calculated angles. All different types of crystal shapes are possible depending on the degrees used.
The artisan will start by screwing the raw crystal into the lapping (cutting) machine, called a chariot, and will then set the angle with a divider. The cutting begins with a regular movement of the wrist. It is important to keep the same angle at all times to avoid irreparable irregularities.
The next stage involves changing the wheel of the machine and fitting a polishing wheel. Each artisan will prepare the polishing wheel using a personally hand-scored knife. The polishing wheel is meticulously cleaned (which is extremely important) and then loaded with course grit diamond powder. The facets are pre-polished, respecting the same angles as the cut. Each piece is verified with a loupe after each stage before receiving the final polish. The process ends with washing and a final quality control. The slightest blemish or fault and the Century sapphire case will be unusable.
Megalith and Monolith
Century has registered patents and certificates for the construction of its sapphire watch cases which are made of two pieces of sapphire that are fused together into one inseparable block. The ‘Megalith’ construction process allows the sapphire crystal case to be assembled to the sapphire crystal watch glass to create an inseparable watch unit, while the ‘Monolith’ technique allows a watch case to be crafted from one single block of sapphire.
The final timepiece
Century’s expertise in the field of sapphire crystals results in timepieces whose cases, bezels and glass (sapphire crystal glass, not mineral glass, of course!) are combined in an incredibly resistant and long lasting timepiece. Each watch will keep its lustre and beauty for years to come. Hours and hours of workmanship go into the creation of each and every piece making Century Time Gems unique and magical.
To see the latest Century’s collections, make sure you don’t leave BaselWorld before visiting the company’s stand at C27 in Hall 1.0.
Source: Europa Star April - May 2011 Magazine Issue