1968 GMT Master 1675 Case Back

[Danilac]

Hi all,

I recently purchased a 1968 gmt master 1675 (1.807m serial) from an original owner and got the whole watch authenticated as fully original, except doubts about the case back… the case back is genuine Rolex case back but not engraved with a year, hence wanted to see if that is common or most likely a replacement one.

Cheers!

[Tom1675]

should definitely have a quarter/year... If the caseback is not original, then what makes you certain there are not other replacement parts?

Pics are a must on this forum and get as many posted as you can...

[Danilac]

Originally Posted by Tom1675

should definitely have a quarter/year... If the caseback is not original, then what makes you certain there are not other replacement parts?

Pics are a must on this forum and get as many posted as you can...

I’ll upload some pictures shortly.

I got it from original owner’s son (have proof of original ownership and don’t think they’d be capable of faking) and took it to a watchmaker with 40+ years of experience with Rolexes and a serious/seasoned vintage Rolex collector. The collectors only issue was with the case back doesn’t have dating but said it’s an original Rolex caseback.

The movement checks out, the lume is uniform and checks out for color/luminescence/ puffiness of this era, serial number checks out, front and back of bezel insert checks out, mark 1 dial checks out (slightly cleaned up but not reprinted or relumed), bracelet matches serial 4th quarter 68, silver date disk with correct font, crystal 50/50 not original (I don’t care though), correct hands for the serial, etc…

curious why a later case back might have been put on… and what it might imply

[Danilac]

Originally Posted by Tom1675

should definitely have a quarter/year... If the caseback is not original, then what makes you certain there are not other replacement parts?

Pics are a must on this forum and get as many posted as you can...

Added photos. Had a watchmaker with 40 years experience, a serious and seasoned vintage rolex collector take an in depth look with a loop, and my own research of this forum + gmtmaster1675 reference website. Everything adds up and matches for serial number/era except the caseback, which is strange to me.

Essentially trying to figure out why someone would replace a caseback/ is it a common part misplaced during service etc.

[Dan S]

Yes, there should be a [quarter].[year] engraving in the case-back in that era. Does it say 1675? Photos please.

[Danilac]

Photos

[Danilac]

Originally Posted by Dan S

Yes, there should be a [quarter].[year] engraving in the case-back in that era. Does it say 1675? Photos please.

Does say 1675, just added photos

[CTech]

There are many reasons for replacement case backs being fitted, but one of the common ones is that the original had a deep engraving and it was easier/cheaper to fit another one rather than have the engraving filled and machined.

A watch with a personal engraving usually sells for less than one with a clean case back.

Sometimes a family member wants to keep the engraved case back as a memento when they choose to sell the watch, especially if the engraving is something personal like a military service number or a message from Mother to Father, etc.

[ADINVA]

Originally Posted by CTech

There are many reasons for replacement case backs being fitted, but one of the common ones is that the original had a deep engraving and it was easier/cheaper to fit another one rather than have the engraving filled and machined.

A watch with a personal engraving usually sells for less than one with a clean case back.

Sometimes a family member wants to keep the engraved case back as a memento when they choose to sell the watch, especially if the engraving is something personal like a military service number or a message from Mother to Father, etc.

Sounds reasonable. Does make sense.

[Dan S]

It's not exactly common to replace the case-back, but not unheard of, especially if it is damaged or corroded. It's more desirable to have the original case-back, but a service replacement isn't a deal-breaker, just factor it into the price.

Of course, any time something is replaced, you want to look more closely at everything else. In this case, I'd suggest asking some of the experts to take a good look at the insert. Obviously the printing is badly offset, but I'm not knowledgeable enough to know if the printing is within the variance one would expect to see in that era, when things were not perfect.

[Lol-x]

1675 = 1 June 1975.

I don't think a date is mandatory on a caseback where it is swapped out on service.

[TimeToGo]

.
Just imagine if it read 16750... No difference..

[lee fowler]

The caseback from my 1.8 Million GMT.

[TuRo]

Service indeed.

I don't care too much about polishing, but personally not be keen on a service caseback on a ate stamped pre-73/74 piece, any more than a service 4m midcase - but everything is about being reflected in price imho...if it's taken into account then fine !

I'd knock at least £1500-2000 (or lot more if gilt ) for a 1675 with a generic service caseback and as much as £8000 + say for an early 6239/40 Daytona or 6538/5510 Sub or 6542 GMT with one....more for rarer early subs !

[springer]

Case backs get replaced - especially one where the outer threads were severely stripped during case back removals, by dropping the case or damaged in other ways. It happens!

The value difference between an original or a service case back is not very significant. I would leave it alone.

[jerseybean]

The number lettering on the caseback is very spaced out plus the case back looks like it was lasered in rather than stamped in.

[TimeToGo]

Originally Posted by jerseybean

The number lettering on the caseback is very spaced out plus the case back looks like it was lasered in rather than stamped in.

That's a good call. Now looking at the details:
.

[TuRo]

Originally Posted by jerseybean

The number lettering on the caseback is very spaced out plus the case back looks like it was lasered in rather than stamped in.

There’s years and years of end link indentations in the case if you look carefully. FYI - Fakers can not replicate that.

[Danilac]

Thanks everyone for the insight and responses! Much Appreciated :)

[Tools]

I am amazed that the case itself is devoid of any signs of the typical corrosion that you find in watches from the era.

[jerseybean]

Originally Posted by Tools

I am amazed that the case itself is devoid of any signs of the typical corrosion that you find in watches from the era.

Freshly made in Vietnam or China, even the metal looks very different frrom Rolex metals. That's always a good way to spot the fakes as the metals look different - also on fake movements and parts.

[TimeToGo]

Originally Posted by jerseybean

Freshly made in Vietnam or China, even the metal looks very different frrom Rolex metals. That's always a good way to spot the fakes as the metals look different - also on fake movements and parts.

Thanks for your input!

[Dan S]

Originally Posted by jerseybean

Freshly made in Vietnam or China, even the metal looks very different frrom Rolex metals. That's always a good way to spot the fakes as the metals look different - also on fake movements and parts.

The case hardly looks freshly made.

[alwayshere]

Originally Posted by jerseybean

Freshly made in Vietnam or China, even the metal looks very different frrom Rolex metals. That's always a good way to spot the fakes as the metals look different - also on fake movements and parts.

Please please.... don't add controversial and unfound comments to threads. Its not only misleading but also confusing as hell for others.

[springer]

The case looks over 50-years-old if that makes it freshly made!

[PVR]

Ok, so let's get into this. The case and caseback are genuine. If the case is indeed 1.8m serial (no engravings have been shown) then the caseback has been swapped. The fonts on the caseback are also genuine, I have found this particular font to be found on case backs around 1973-1974, immediately after the dated case backs. After 1974, the fonts change again inside the casebacks. If the engraving is a 2.8 and not 1.8 then I think that it could be original to the case.

I would also argue that the value difference for an incorrect caseback is insignificant. I think it would be very significant, perhaps $1000-2000 less for incorrect case back.

[alwayshere]

Originally Posted by PVR

Ok, so let's get into this. The case and caseback are genuine. If the case is indeed 1.8m serial (no engravings have been shown) then the caseback has been swapped. The fonts on the caseback are also genuine, I have found this particular font to be found on case backs around 1973-1974, immediately after the dated case backs. After 1974, the fonts change again inside the casebacks. If the engraving is a 2.8 and not 1.8 then I think that it could be original to the case.

I would also argue that the value difference for an incorrect caseback is insignificant. I think it would be very significant, perhaps $1000-2000 less for incorrect case back.

your final paragraph is a little confusing for me - are you saying incorrect caseback is significant to value or insignificant?

I would have thought for this model, the difference is immaterial. I mean, who's going to look at the inside of a caseback? its not an optically obvious feature like a dial, insert, hands which obviously holds more value. Secondly, its also not a particularly "rare" reference... 1675s are frequently found. If it was 6452 or a 6538... then yeah maybe.

[TuRo]

Originally Posted by PVR

Ok, so let's get into this. The case and caseback are genuine. If the case is indeed 1.8m serial (no engravings have been shown) then the caseback has been swapped. The fonts on the caseback are also genuine, I have found this particular font to be found on case backs around 1973-1974, immediately after the dated case backs. After 1974, the fonts change again inside the casebacks. If the engraving is a 2.8 and not 1.8 then I think that it could be original to the case.

I would also argue that the value difference for an incorrect caseback is insignificant. I think it would be very significant, perhaps $1000-2000 less for incorrect case back.

Even if 2.8 million (which is 70/71 using the most accurate VRF case/caseback dating project below *), I'd suggest respectfully, it couldn't be original as casebacks had year and qtrs then and for another couple of years thereafter.
*http://vintagerolexforum.info/vrf/index3.html
#Apologies to David in Stockholm ;-)

[PVR]

"Even if 2.8 million (which is 70/71 using the most accurate VRF case/caseback dating project below *), I'd suggest respectfully, it couldn't be original as casebacks had year and qtrs then and for another couple of years thereafter."

What are you saying? Case backs were no longer date stamped after 1972. Where does 2.8m come into this? The OP said the watch was 1.8m, so it would have to have a date code. I agree that a 1970, 71 and even 72 case backs should be date stamped.

This one is not date stamped so it is not original to this watch but it is a genuine 1675 Case back.

I think there is some confusion here. The caseback on this watch is from 1973/74 and is not and should not be date stamped, but THIS case back is not original to THIS watch.

[TuRo]

Originally Posted by PVR

"Even if 2.8 million (which is 70/71 using the most accurate VRF case/caseback dating project below *), I'd suggest respectfully, it couldn't be original as casebacks had year and qtrs then and for another couple of years thereafter."

What are you saying? Case backs were no longer date stamped after 1972. Where does 2.8m come into this? The OP said the watch was 1.8m, so it would have to have a date code. I agree that a 1970, 71 and even 72 case backs should be date stamped.

This one is not date stamped so it is not original to this watch but it is a genuine 1675 Case back.

I think there is some confusion here. The caseback on this watch is from 1973/74 and is not and should not be date stamped, but THIS case back is not original to THIS watch.

No I'm saying the opposite - they were date stamped after 70/71 and the 2.8 mil came from your possible supposition :

''If the engraving is a 2.8 and not 1.8 then I think that it could be original to the case.'' end of your first paragraph!

Either way, we agree it is not original to watch :-)