Seiko SQ, Ref. 5H23-6230, Cal. 5H23, Men’s Quartz, 1987

Oversized blue minute numerals and a diagonal blue-grey stripe make this 1987 Seiko SQ immediately recognizable. Reference 5H23-6230 combines a grey dial, kanji day-date display and Japanese 5H23 quartz analog caliber in a compact 33 mm steel case. A new black NATO strap brings out the practical, casual character of its graphic design.

Blue numerals and kanji day-date

Large blue numerals mark the five-minute intervals, accompanied by small applied dot markers and an outer minute track. The diagonal blue-grey band runs toward the calendar aperture at 3 o’clock. Seiko and Quartz are printed on the left side, with the SQ emblem in the lower half. The grey surface shows modest patina and light age marks.

Bold white, blue-outlined baton hour and minute hands contrast with the dial, accompanied by a slender central seconds hand. The calendar displays a numerical date and a kanji weekday indication.

Compact steel case and new NATO strap

The round stainless steel case has a polished bezel, small lugs and a curved profile, measuring 39 mm lug to lug. Visible scratches and wear remain on the surfaces. Protective shaping partly surrounds the ridged steel crown at 3 o’clock, with a small adjacent side detail adding to the technical appearance.

A new black nylon NATO strap fits the 18 mm lugs. It is adjustable and contrasts with the grey dial and steel exterior. The strap is a replacement accessory, separate from the original watch-head components.

Seiko 5H23 quartz operation

The Japanese Seiko 5H23 quartz analog movement powers the time and day-date indications without daily winding. The watch is fully operational; it is not offered as fully serviced. Its watch-head components are original, with the new strap treated separately. No box or papers are included. It comes with a 12-month warranty, and Vintage Watch Studio ships worldwide.