HELP ME TO IDENTIFY A RARE IWC WATCH THAT I`HAVE

I`VE A IWC WATCH, IT SEEMS LIKE ORIGINAL, THERE IS NO SIGN TO BE FALSE.
I WAS SEARCHING FOR, AND I FOUND THAT IT SHOULD BE FROM THE YEAR 1917, VERY OLD AND VINTAGE WATCH WORKING.

THE DIAL IS IN GOOD CONDITION, THE CASE IS IN SILVER 0,875 AND WITH THE IWC STAMP. 

THE MAIN QUESTION IS, THE WATCH IS A WRISTWATCH, BUT IS VERY MUCH SIMILAR WITH POCKET WATCH.
HAVE LIKE 2 CASEBACKS, ONE MAIN CASEBACK THAT OPEN TO THE SIDE (AS A POCKET WATCH) WITH THE INTERNAL STAMPED THE NUMER 730712 (SO I THINK THE CASE NUMBER IS THIS, 730712), ALSO HAVE THE IWC STAMP AND SILVER 0,875 SYMBOL ON THAT.

WHEN I OPEN THE "FIRST CASEBACK" THAT I ALREADY MENTIONED, BELOW HAVE A OTHER ONE WITH INTERNATIONAL WATCH CO. STAMPED ON THAT. AFTER OPEN THIS "SECOND CASEBACK" SO I CAN SEE THE MACHINARY. 

THE MACHINARY IS A MANUAL WIND WITH THE NUMBER 677575.

THE WATCH HAVE A NORMAL CROWN (AS WRISTWATCH), NOT A CROWN SIMILAR THAN A POCKET WATCH.
THE DIAL IS WHITE, WITH THE NUMBERS FROM 1 TO 12 IN BLACK, AND INTERNAL CIRCLE OF NUMBERS IN RED FROM 13 TO 24 AND SMALL SECONDS IN POSITION OF 6H. 

THE CASE HAVE 33 MM OF DIAMETER WITHOUT THE CROWN.

MY WATCH IS A WRISTWATCH.

MY DOUBT IS, THIS IS A REAL WRISTWATCH OR IS A POCKET WATCH ADAPTED/CONVERTED TO A WRISTWATCH?

I OBSERVATION IS THAT THE POCKET WATCHES FROM THAT TIME USUALLY HAD AROUND 46-60MM AND MY WATCH HAVE 33MM (THE SIZE OF WRISTWATCHES ON THAT TIME USUALLY).

CAN YOU HELP ME TO IDENTIFY THE MODEL OF MY WATCH, THE CORRECT YEAR AND IF IS ALL ORIGINAL IN THE WAY THAT IS NOW OR IS CONVERTED? 

I REALLY LIKE THIS WATCH AND WANNA KNOW ABOUT THAT, CAUSE IS RARE AND VERY OLD, MORE THAN 100 YEARS PROBABLY.

I APPRECIATE SO MUCH. 

Hello Arthursoares.

Welcome to the Forum.
It would be very helpfull to share some pictures of your watch for identification.

Best

Andreas

1. Is it a wristwatch or converted pocket watch?

Based on your description:

• 33 mm diameter case (too small for pocket watch)
• Normal wristwatch crown (not a pendant crown)
• Small seconds at 6 o’clock
• Double caseback system (outer hinged + inner dust cover)
• Manual wind movement
• Silver 0.875 case with hallmarks

👉 This strongly suggests:

It is a purpose-built wristwatch using a pocket-watch-style movement architecture — NOT a later conversion.

Why?

In the 1910s–1920s, IWC and other Swiss makers:

• Took small pocket watch calibers
• Re-cased them in wristwatch cases (called “trench watches” or early wristwatches)
• Often kept hinged covers and dust lids

So your watch is likely:

A transitional early wristwatch (WWI-era design philosophy)

2. About the “two casebacks”

What you described is very important:

• Outer hinged back → typical “hunter-style” protection (very WWI/early wristwatch design)
• Inner dust cover marked “International Watch Co.”

👉 This is original construction, not modification.

Converted pocket watches usually:

• lose inner covers OR
• show mismatched case machining

Yours sounds factory-made.

3. Serial numbers (key clue)

• Case number: 730712
• Movement number: 677575

IWC serial ranges suggest:

👉 circa 1915–1919 production window

This matches your assumption of ~1917 very well.

4. What model is it?

IWC did not use “model names” like modern watches back then.

Instead, it would likely fall under:

• Early IWC wristwatch (trench watch era)
• Possibly based on a small Savonette or Lepine pocket caliber adapted for wrist use

So the correct identification is usually:

“Early IWC trench wristwatch with converted pocket-watch movement (circa WWI era)”

5. Is it original or modified later?

From your description:

✔ Likely ORIGINAL

• Matching case and movement era
• Correct IWC stamping inside both covers
• Correct silver hallmark (0.875 is period correct)
• Consistent dial style (24-hour red track + small seconds)

❌ Unlikely to be later conversion because:

• Size is correct for wristwatch production
• Crown type matches wristwatch design
• No mismatch between movement and case era indicators

6. Important insight about rarity

This type of watch is:

• Historically important (WWI transition design)
• Not “luxury rare” but collector historically rare
• More valuable for original condition + matching parts

Final conclusion

Your watch is most likely:

✔ A genuine IWC early wristwatch from approx. 1915–1919
✔ Built using pocket-watch-style movement architecture
✔ Factory-cased, not a later conversion
✔ Part of WWI-era “trench watch” evolution

These are the pics of the Watch that I mentioned. Maybe can be better to you help me identify. Thank you all a lot