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Meet the Seiko Presage Sharp Edged Open Heart “Shironeri” and “Aisumi” Watches

The two new Open Heart Midday and Midnight watches from Seiko's Sharp Edged series feature a unique hemp leaf-inspired geometric dial pattern in unbleached white and deep indigo blue. Each model provides a glimpse of the new Calibre 6R38 movement through an open heart aperture at 9 o’clock


You could say that the Seiko Presage Sharp Edged watches are edging nearer to the style of a Grand Seiko. They feel incredibly crisp and sleek – certainly refined enough to wear with best attire. Their strong lines, flat surfaces and dials that nod to both modern and traditional Japanese culture are a play on motifs and textures, adding a heightened sense of depth to their designs. For 2022, Seiko has released five new Presage Sharp Edged watches. There’s a limited edition GMT with a rich blue textured dial that echoes the colour used by Ukiyoe artists over the centuries to create images of Mt Fuji in high summer. There are two Power Reserve models; a ‘Geppaku’ Moonlight and ‘Kuritobi’ Russet variation with an accompanying days-of-the-week and pointer-style date ring. Lastly, there are two Presage Sharp Edged Open Heart watches, which we’re going to take a closer look at today.



The new Seiko Presage Sharp Edged Open Heart watches (also named the Midday and Midnight) have, as their name suggests, an open-heart aperture that reveals part of the oscillating balance wheel and escapement of a new calibre belonging to the 6R movement series. The two new models go by the references; SPB309 “Shironeri” and SPB311 “Aisumi”. New, like the Presage Sharp Edged Power Reserve watches, is their case design, with friendly dimensions of 40.2mm. They sit upon the wrist at a height of 11.8mm and feature top and side surfaces that are faceted and mirror polished, adding a whole new level of sophistication and luxury to their architecture. In addition to this, their brushed and polished stainless steel cases are finished with a super hard coating and feature an inward tapering design that draws the size of the case in further, for a more compact feel.



The Seiko Presage Sharp Edged Open Heart ref. SPB309 boasts a beautiful unbleached silk white dial colour with a striking blued steel central second hand and tapering sword-like central hour and minute hands that have been treated with a strip of luminous material. The hands are baton style, surrounded by a deep blue outer minute track. If you look to the 9 o’clock location, you can see that the index has been cut through, to accommodate enough room for the circular open heart aperture. The Seiko Presage Sharp Edged Open Heart ref. SPB311 presents the time on a deep indigo blue colour and features rose gold coloured baton indexes and hands. Both iterations have displays that are executed with the hemp leaf-inspired pattern seen in the other three additions of the new 2022 Sharp Edged watch series. The hexagonal pattern is inspired by the Asanoha plant. This geometric surface, contrasting in shadows and angles of brilliance, is Japanese-inspired and follows the pattern used in Japanese fabrics since the Heian period, spanning thousands of years. The fast-growing plant develops into a tall, straight tree in just a matter of months and can be grown all year through. Its hexagonal-like hemp leaves are still associated with growth and good health today.



Both the two Seiko Presage Sharp Edged Open Heart SPB309 “Shironeri” and SPB311 “Aisumi” models expose the escapement and oscillating weight of the new Calibre 6R38 through their dials. Specially adapted to allow the wearer to see the beat of the escapement through the opening at the 9 o’clock position, the movement offers an impressive power reserve of 70 hours and beats at a rhythm of 21,600 vibrations per hour. The Calibre 6R38 also comprises a total of 24 jewels and puts its performance and arrangement on show through the reverse side of the case also. A sapphire-backed exhibition feature enables a clear view of the movement and its decoration. The same anti-reflective material is also used for the top of the watch’s 100-meter water-resistant stainless steel case. The robust structure of the case is also integrated with magnetic resistant technology that protects the movement from magnetic fields reaching up to 4,800 A/m.


The Seiko Presage Sharp Edged Open Heart ref. SPB309 with a white dial is fitted on a matching stainless steel bracelet with links executed in a mix of brushed and polished surfaces. It secures to the wrist with a three-fold clasp and a push-button release mechanism. The Seiko Presage Sharp Edged Open Heart ref. SPB311 with a deep indigo blue dial is finished on a deep brown calf leather strap that compliments the luxurious rose gold accents on the dial perfectly.



If you’d like additional information on either of the two new Seiko Presage Sharp Edged Open Heart watches, you can explore the spec list on the ref. SPB309 here and the ref. SPB311 here. Alternatively, you can call and speak to a member of our Jura Watches sales team on 01335 453453


Technical Specifications of the new Seiko Presage Sharp Edged Open Heart watches

  • Case: 40.2mm – height: 11.8mm - stainless steel – super hard coating – brushed and polished – new polished facets – inward tapering design – 100-meter water-resistant – anti-reflective sapphire crystal glass front – sapphire exhibition caseback
  • Dial: Unbleached white / deep indigo blue – hemp leaf textured dial surface inspired by the Asanoha plant – silver indexes / rose gold coloured indexes - luminous central sword-shaped hour and minute hands – open heart aperture at 9 o’clock
  • Movement: Calibre 6R38 – Seiko’s 6R movement series – 6 beats per second – 21,600 vph – 70-hour power reserve – 24 jewels
  • Straps: Stainless steel – bracelet – three-fold clasp and push-button release mechanism / dark brown calf leather strap
  • Reference: ; SPB309 - “Shironeri” / SPB311 “Aisumi”
  • Price; £860
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