Welcome to our ongoing series of short articles about watches which should only take a minute or two to read. We continue today with a brief discussion of the tourbillon.

Tourbillon

In horology, a tourbillon (/tʊərˈbɪljən/; French: [tuʁbijɔ̃] "whirlwind") is an addition to the mechanics of a watch escapement. Developed around 1795 and patented by the French-Swiss watchmaker Abraham-Louis Breguet on June 26, 1801, a tourbillon aims to counter the effects of gravity by mounting the escapement and balance wheel in a rotating cage, to negate the effect of gravity when the timepiece (thus the escapement) is stuck in a certain position. By continuously rotating the entire balance wheel/escapement assembly at a slow rate (typically about one revolution per minute), the tourbillon averages out positional errors.

Originally an attempt to improve accuracy, tourbillons are still included in some expensive modern watches as a novelty and demonstration of watchmaking virtuosity. The mechanism is usually exposed on the watch's face to show it off. -- Source: Wikipedia

Ok, so what does that really mean to a watch buyer?

In a conventional mechanical watch movement, the balance wheel oscillates back and forth (by virtue of the hairspring). As it swings, it engages the escape wheel via a forked lever, releasing the torque supplied by the (much larger) mainspring located at the other end of the gear train. The balance wheel, the lever and the escape wheel are all at fixed locations on the movement's base plate (aka Main Plate). However, with a tourbillon, these 3 components are held together in a "cage" which rotates (typically once per minute) when the movement is operating.

Why go to the trouble and expense of doing this? Well, two centuries ago, it was done to average out the rate error between having a watch in various positions (face up on a night stand, held vertically in a watch pocket, etc.). Note that clocks have no need for a tourbillon since they remain in one orientation. Well, except for marine clocks and they were often mounted in a box with gimbals to overcome the same problem (gravity induced positional timekeeping error).

Now days, the theoretical timekeeping edge is just not really much of a demonstrated advantage. Some tourbillons may (or may not) keep better time than a similar movement with a conventional (fixed) escapement.

So why buy a tourbillon? Because they are often exposed on one or both sides of a watch. The animation they provide is a visual treat for watch collectors.  On a watch with a so-called "open heart" conventional movement, you can see the balance wheel oscillating and if you look closely you may see the escape wheel turning. This is considered to be a cheesy imitation of a real tourbillon.

In comparison, with a tourbillon, an entire set of bound together components are spinning as a single unit. The balance wheel still oscillates and the escape wheel spins on its axis while rotating along with the other items within the tourbillon's cage. Lot's more moving stuff to see (and appreciate).

So why isn't every mechanical watch a tourbillon? Cost of course! There are many more small and precisely made parts in a tourbillon. Plus since the balance wheel and the hairspring's attachment point are rotating, it is much harder to regulate a tourbillon.

Another factor is market positioning. The Swiss have basically said that they won't produce a tourbillon for under $15,000 (and most are over $40,000). As they use this "complication" (really it is not a complication in the strict definition of the word) only on their higher priced watches.

There are Chinese tourbillons which you may be able to find for around $500 (and up) and they do provide the same animation. However the time keeping (accuracy) and overall watch quality is in line with what you get from a cheaply made Chinese watch.

Times up! That's all for today. Stay tuned to the Hawaii Jewelers Association website for the next installment of "The Minute Hand" with your host, Mark Carson of Mark Carson / Individual Design watches.

Welcome to our ongoing series of short articles about watches which should only take a minute or two to read. We continue today with a brief discussion of watch crystals.

Watch Crystals

The crystal on a watch is the "glass" that covers the dial and hands.

There are basically 3 types of crystals used on watches these days. And really, only 2 of them are commonly used anymore.

• Mineral Crystal - which is a fancy way of saying hardened glass. Even though hardened, it can be scratched by contact with steel, brick, etc. so you should avoid scraping a mineral crystal against things. Advantages: low cost and better impact resistance than sapphire. Disadvantages: scratches somewhat easily and cannot be repaired (typically replaced if damaged).
• Sapphire Crystals - man made, synthetic sapphire. They are chemically and structurally the same as  natural rubies and sapphires - all of which are corundum, an aluminium oxide. If a sapphire is red in color, it is a ruby. Otherwise any other color (including colorless as is used on watch crystals) is called a sapphire. So while we often think of sapphires as only being blue, this is not always the case.  The jewels in a watch movement are typically man-made rubies. So outside of their red color, they are the same material as a watch's transparent sapphire crystal over the dial and hands. Advantages: very hard (9 on the Mohs scale - where diamond is 10). Disadvantages: more costly than mineral crystal (glass) and it can be chipped or shattered more easily than hardened glass. Once chipped, it can not be repaired (only replaced).
• Plexiglass - an acrylic  plastic. A particular brand of plexiglass known as "Hesalite" has been used by Omega on their famous Speedmaster chronographs since they went to the moon with the Apollo astronauts Neil Armstrong and Buzz Aldrin in 1969. While it is possible to buy a new Speedmaster today with a plexiglass crystal, most new Speedmasters have sapphire crystals. Plexiglass has been used for watch crystals since the 1950s and it is highly impact resistant. You can beat on a piece of plexiglass with a hammer and while you will no doubt deeply scratch it, it is extremely tough and shatter resistant. Even with normal use (no hammering), scratches are common on plexiglass crystals. However, using abrasives many scratches can be polished/buffed out. Advantages: low cost compared to sapphire and virtually unbreakable. Disadvantages: scratches very easily and is not as transparent as mineral crystal or sapphire.

Crystals may be flat or domed (curved). If a crystal is only domed on one side, it will act as a magnifier and will distort your view of the dial and hands. A double domed (curved top and bottom: convex and concave respectively) crystal avoids distortion while still having a pleasing domed appearance and feel.

Anti-reflective (A/R) coating are often (but not always) applied to a watch crystal to help minimize unwanted reflections that make it harder to read the time. If applied to just one side, it will be coated on the bottom (inside) surface where it will avoid being scratched. A doubled coated crystal has A/R coating on both the top and bottom surfaces of a crystal. This does a better job of eliminating reflections but the top coating may be scratched as the coasting is not nearly as hard as the sapphire crystal upon which it is usually applied.

"Flame Fusion" is a marketing term used by low end watch brand Invicta for some of their crystals. This appears to just be a thin layer of sapphire applied on top of a piece of mineral glass. It is generally considered to be a low cost, inferior product compared to a true sapphire crystal.

Another, historically interesting, crystal material was a piece of natural quartz which was used on the famous "Marie Antoinette" watch made by Abraham-Louis Breguet (the most famous watchmaker of all time). This is probably the most famous watch of all and was not even completed during the lifetimes of either Marie Antoinette or Breguet. To read more about this fascinating watch, pick up a copy of the book  "Marie Antoinette's Watch" by John Biggs -  Available on Amazon.

Times up! That's all for today. Stay tuned to the Hawaii Jewelers Association website for the next installment of "The Minute Hand" with your host, Mark Carson of Mark Carson / Individual Design watches.

Welcome to a new series of short articles about watches which should only take a minute or two to read. We will start with "Watches 101", truly the basics and build from there. There are exceptions to every "rule" but the following are generally correct and help to get the nomenclature and concepts across.

Watch Basics

Watch part names:

• CROWN - the knob which is used to set the time. On a mechanical watch it's also used to wind up the main spring which powers the watch.
• BEZEL - the ring around the dial on the outside of the watch. This may be fixed or it may rotate (diver's watches often have a rotating bezel with minute markings).
• DIAL - the "face" of the watch which usually have markings to indicate hours and minutes/seconds.
• HANDS - the analog pointers which reside above the dial. A "3 hand watch" has an hour hand, a minute hand and a seconds hand. A "2 hand watch" has no seconds hand.
• LUGS - the "horns" on the case to which a strap or metal bracelet is usually attached.
• MOVEMENT - the "engine" beneath the dial that contains the time regulation (quartz or mechanical) and gears which drive the hands.
• STRAP - a non-metal band which attaches a watch to your wrist. Often made of leather or other flexible materials.
• BRACELET - a metal band usually made with a number of links.
• CRYSTAL - the transparent cover over the dials and hands. Usually made from Mineral Crystal (which is really hardened glass) or Sapphire (which is a clear, man-made sapphire crystal that is highly scratch resistant).

Types of watches:

• QUARTZ - battery operated and time regulated via an quartz crystal, the second hand jumps from one second to the next. Generally less expensive than an mechanical watch of similar quality. Much more accurate than mechanical watches. Accuracy is usually within a few seconds per month. Quartz watches may have digital displays (such as LCD or even LEDs in older watches) or they may have analog hands.  Quartz watches with analog hands are sometimes referred to as "Mecha-Quartz", but they are still "quartz watches", not "mechanical watches" despite their hands and some gears.
• MECHANICAL - powered by a main spring (no battery) and time regulated via a balance wheel and hair spring. Sweep second hand: the seconds hand makes 2.5 to 5 small movements per second which makes the hand appear to be sweeping in a more continuous motion compared the 1 second jumps on the typical quartz watch. Accuracy is usually to within a few seconds per day.

Types of mechanical watches:

• MANUAL or also known as HAND WIND - the main spring which powers the watch is wound when you twist the crown clockwise. Most affordable hand wound watches need to be wound every day to keep good time and will stop if not wound after about 2 days.
• AUTOMATIC or also known as SELF-WINDING - when worn, the main spring which powers the watch is wound by the gravity driven spinning of a weighted rotor (which is attached to the bottom of the movement). Automatic watches will be kept wound if worn daily, but otherwise, like a manual wind watch, will run out of power if not worn or wound for a day or two. Most automatic watches can also be wound by hand.

Times up! That's all for today. Stay tuned to the Hawaii Jewelers Association website for the next installment of "The Minute Hand" with your host, Mark Carson of Mark Carson / Individual Design watches.