Here is a quote of a post made on SCWF by Zami Zahari (aka StratmanII), some time ago, here:
StratmanII said:The many faces of the Citizen Nighthawk (+pics)
I did a bit of looking up on the amazing Citizen Nighthawk. Most of us are already familiar with the U.S version Nighthawk and some own the so-called Euro Nighthawk with that wonderful caseback.
I'm primarily a Seiko collector and the Nighthawk was my first Citizen since 1983. I found the large sunken dial, the pseudo-retrograde GMT hour scale and the highly detailed, internally rotating E6B flight rule bezel quite attractive. The blue lume is also a refreshing departure from the usual green lume in my Seiko collection.
If you'd like to know a bit about all the Nighthawk models, do read on.
(All photos depicted belong to their respective copyright owners)
The U.S. Nighthawks
This is probably the most common Nighthawk model sold in North America and to some extent, in the U.K.
You can easily identify by the Nighthawk text on the dial. Non-U.S. Nighthawks do not have this text. The U.S. Nighthawk also sports full lumed indices and framed Arabic numerals.
The down side of the U.S. Nighthawk is the plain vanilla, highly polished caseback with laser etched text. Many U.S. Nighthawk owners lamented Citizen's choice of this caseback instead of the highly detailed, engraved satin caseback on the European and Asian variants.
The U.S. Nighthawk caseback vs the non-U.S. version:
You can easily see why the latter caseback is more desirable among Nighthawk owners.
There are also variants such as the PVD'ed black S/S and titanium versions. Here is the full lineup of the U.S. Nighthawks:
BJ7000-52E (Stainless Steel)
BJ7005-59E (Black ion plated, S/S)
BJ7000-01E (Leather strap version, S/S)
The Asian Nighthawks
The Asian counterparts of the U.S. Nighthawk come without the "Nighthawk" text on the dial. They also have partly lumed metal indices which help give the dial a classy look. In addition, the "12" and "6" numbers aren't raised like the U.S. versions.
What makes these Nighthawks interesting is the wonderful engraved caseback.
BJ7010-59E (Stainless Steel)
BJ7005-54E (Black ion plated, S/S)
Newer variations of the Asian Nighthawks appeared recently with the original Citizen deployant leather straps:
BJ7010-24W (Brown, S/S)
BJ7010-16F (White chapter ring, S/S)
The Japanese Nighthawks
Japan market Nighthawks are identified by the "Made in Japan" text located on the dial, at the 8 o'clock position. It's a bit too small to see, but it appears on large photos. JDM Nighthawks are the Radio Controlled versions and can synchronize the time with LF (Low Frequency) radio time signals on long wave. Alas, the Radio Controlled Nighthawks lack the 24-hr GMT scale found on the garden variety Nighthawks.
The easiest way to tell a JDM Nighthawk is by the "W.R. 20 Bar" text on the dial.
The caseback of the JDM Nighthawk is also richly detailed. The titanium versions are coated with Citizen's famous Duratect plating technology. Interestingly, Duratect is only used on the Japanese titanium versions.
Other interesting variants of the Japan Nighthawks:
PMD56-2771 (S/S version)
PMD56-2774 (Black leather strap)
PMD56-2775 (Brown dial with matching strap)
There are yet other more exotic Nighthawks, such as the PMP56 series with all the bells and whistles. They're the most expensive of the lot and departs from the usual Nighthawk design. You get a dedicated GMT subdial, alarm, three main city times (London, Paris & New York) and perpetual calendar capability.
These "Ultimate" Nighthawks come in two versions:
PMP56-2902 in blue!
Finally, let's take a look at the:
These Euro Nighthawks are also Radio Controlled but differ from their Japanese counterparts by the lack of "W.R. 20 Bar" text. In its place, the text "Sapphire" is printed, indicating the use of sapphire crystals, obviously.European Nighthawks have the model number starting with "AS".
AS2031-57E (Stainless steel)
AS2031-57F (White chapter ring)
AS2031-06WP (Interesting combo - brown dial with reptile skin-like strap)
AS2031-57 (Thought you'll never see a blue Nighthawk, eh?)
Here's an all-blue Euro Nighthawk!
I could've missed a few other variants out there, so feel free to add any info.
Thanks for reading!