Contact Us

Use the form on the right to contact us.

You can edit the text in this area, and change where the contact form on the right submits to, by entering edit mode using the modes on the bottom right. 

2825 Sand Hill Rd
Menlo Park, CA, 94025

(650) 292 0612

Stephen Silver is renowned for our extraordinary ability to procure, design and handcraft the world's finest jewelry and gemstones.

The Stephen Silver Fine Jewelry Estate Collection includes some of the finest pieces from the Edwardian, Victorian, Art Deco, Art Nouveau, and Retro eras. Signed and period pieces are the company's specialty; many of which are from prestigious jewelry houses such as Cartier, Van Cleef & Arpels, Bulgari, Tiffany & Co., and Harry Winston.

The Stephen Silver Fine Jewelry Signature Collection exemplifies modern day luxury combined with old world elegance to produce true works of art. Exquisitely handcrafted in platinum and 18-karat gold, using only the very finest diamonds and colored gemstones, our Signature Collection is exceptional in quality and extraordinary in style.

Understanding What a Certified Chronometer Watch Is and How It Is Rated

Watches

Understanding What a Certified Chronometer Watch Is and How It Is Rated

Annena Sorenson

With summer here and everyone focused on sports watches and timepieces that can keep up with their rugged, active lifestyles, it's a good time to take a closeup look at what it means when a watch is a certified chronometer.

Chronometer roots date back to the 18th century when ships at sea were running aground because they had no way to determine longitude. A race was on amongst the seafaring countries to develop an onboard instrument that could keep accurate time and calculate longitude. When the first such pieces were made for ships they were referred to as chronometers and were considered the most rugged, durable timepieces to date.

Today, many watch brands insist that their high-precision watches house a movement that can keep up with the active pace of today's individuals. This means putting them through stringent testing in different positions and in all sorts of conditions (water, weather, humidity, pressure, etc.).

Generally, a chronometer is rated under laboratory conditions in a specified testing institute and is then certified as having passed those tests within certain ranges of accuracy and precision. There are several chronometer testing institutes around the world (Germany has the Glashutte Observatory in Saxony; France has the Observatory at Besancon), and some brands test their watches in-house and certify them accordingly.

The well known testing institute for Swiss watchmaking is the Controle Officiale Suisse des Chronometres – or C.O.S.C. There are three different COSC laboratory testing facilities in Switzerland: Biel/Bienne, Geneva, LeLocle, but they all use the same guidelines and criteria.

Each watch tested must comply with ISO 3159 standards after being tested for five to 15 days in five positions at several different temperatures. Measurements are made daily via cameras and advanced equipment based on comparisons with two independent atomic clocks. After testing, watches must meet an average daily rate criteria of -4/+6 seconds; a mean variation in rate of 2 seconds; a thermal variation of + or – 0.6; and more.

smallimage_08

Certified COSC chronometers have a serial number engraved on the movement and are sold with a certificate. Because of the rigorous testing and high standards, just about 3 percent of all Swiss watches produced are COSC-certified chronometers.

Stop in any time to see the chronometer watches we carry.