From the customer’s point of view, there are currently two distinct ways to view the replica Seiko. In one hand, as the market consensus seems to suggest, Seiko really has become very expensive, and I seem to agree. It did become much more expensive by its own standards. Another way to look at it is to compare today’s big Seiko to its competitors, and then the GS is almost the most powerful ever.
Everything you need to know about Spring Drive technology, including its features and history, you’ll find here. All you need to get about the 9r86/9r96 sport, which is new for the 2019 Seiko big sport spring drive timing, you will find in my comments on his brother, SBGC201.
Where the new SBGC230 & SBGC231 stand out are in their design and presentation, as well as, you guessed it, their price. There is another way of looking at it, though. The SBGC231 costs almost exactly the same as the fake Rolex Oyster Perpetual Cosmograph Daytona in steel. Of course, there is a difference in status and perception between Grand Seiko and Rolex, but the under-the-radar nature of GS is a big plus for some, so we shall leave that out of the equation and nerd out over the technical prowess of these two replica watches.
The Grand Seiko Sport Spring Drive Chronograph GMT SBGC231 is crafted from titanium, a lightweight material generally accepted within industry circles to be considerably more complicated to finish — and to bring it to Zaratsu levels of detailing should be a challenge in itself. Not only is the case material of the Grand Seiko arguably more complex than Rolex’s industrialized 904L steel, but so is its case shape. There is a solid reason why we don’t see massive flat surfaces and hard angles on replica watches — even ultra-high-end watches prefer to avoid such shapes as much as possible. 
Having tried case polishing on some different occasions with different materials, I have experienced how frighteningly easy it is to destroy any one of these edges and angles — and what you’ve taken off, you’ll never be able to put back on. Although I am very painful to say that the Rolex case is very simple and foolproof once you start looking at them that way. They are a very effective design because they can be mass-produced and seen clearly even by untrained people.
Movement-wise it’s a well-known similar story. Rolex achieved borderline technological perfection with the 4130: a column-wheel, vertical clutch chronograph capable of -2/+2 seconds daily rate and a 70-hour power reserve, all in a very compact form. By stark contrast — although Grand Seiko does not do much to communicate the merits of its Spring Drive Chronograph — I managed to find out that its 9R86/9R96 calibers comprise 416 components, more than double that of the Rolex 4130. This entails the addition of a power-reserve indicator, 24-hour GMT display, quickset hours and date over the rather spartan Daytona that depends on a pointless tachymeter scale to raise the perception of complexity. Just as important as all that muscle-flexing is the presence of Spring Drive, as for me, the greatest and most advanced thing to have ever happened in “affordable” mechanical watchmaking.
Add it all together, with a much more complicated case and movement, and you have a fake watch that is not only better than Rolex in every way, but in at least a few ways technically. With a diameter of 44. 5 mm and a case thickness of 16. 8 mm, the GMT SBGC231 has a brutalist edge between retro and futuristic. Its unusual brushed dial is designed to look like a lion’s mane, a symbol of Seiko. The brand won’t say what technology the dial USES, but we know it’s a regular brass base.
