Power Wheels Magazine A Notch Above
A portmanteau is a blend of two words to form a new one. Seiko’s Diamatic model blended “Dia” from Diashock, Seiko’s exclusive shock-proof system, and “Matic” from “automatic” or the self-winding mechanical movement, which were two of Seiko’s significant engineering achievements of the 1960s and 1970s.
For our Timepieces feature this Friday, September 11, 2026, we take a look at our 1971 Seiko Diamatic 7006-6020, which was produced on December 1971 at Daini Seikosha. Similar to the ‘70 Diamatic 7005-6010 that we featured two days ago, our ‘71 Diamatic features a 39 mm polished case that’s 11 mm thick with a 39 mm lug-to-lug length. Instead of a funky steel bracelet, our Diamatic came with a brown raw hide leather strap when we acquired it.
The Diamatic line had a futuristic yet elegant design prevalent during the “space age” craze of the ‘70s. Syringe-style hour and minute hands point to military-style 24-hour numerals printed on the chameleon brown dial that turns dark red or maroon when viewed at different angles. A white vertical strip and a silver outer ring creates contrast and texture to the chameleon dial.
Behind the dial hides a 19-jewel Caliber 7006A movement that turns at 21,600 beats per hour (BPH) and utilizes an eccentric self-winding mechanism with a single gear stage. The 7006A is related to the Seiko 7005 movement, but adds day/date complication with a quick-set function. Because it has no “hacking” function – where the second hand stops when the crown is pulled out – the 7006A is often considered as an entry-level automatic movement.
As a vintage timepiece from the early Seventies, the Seiko Diamatic line has created a niche following among collectors who love 1970s retro-futurism. Our 55-year-old Diamatic 7006-6020 has engineering, reliability, and style that makes it collectible. Its eventual rarity will soon make it valuable.
Model: Seiko Diamatic
Reference No. Month/Year of Manufacture: December 1971
Type: Casual/Field Watch
Movement: Self-Winding/Automatic
Caliber: Seiko 7006A
No. of Jewels: 19
Diameter: 39 mm
Thickness: 11 mm
Lug-to-lug Length: 39 mm
Lug Width: 19 mm
Weight: 59 grams
