Bulova 1958 His Excellency

I'm hard pressed to say it's either, but would confirm it's the C and/or EW. 

Below is 1958 Ad for His Excellency, w/ description which I translate as all HE's have six precision adjustments. 

For subject watch.  Since original mounts come and go, I can ID based on the mount on which the subject watch is now presented.  Leather. 
The first ad in thread indicates "C" on expansion, "EW" on leather. 

I'd go with confirmed 1958 HE "EW" based on all this, or I'd go confirmed generic HE.  IMO the first choice gives more information about the watch.  ... if it were on an yellow gold colored expansion band I would go for 1958 HE "C". 

I think it is not just the band, if at all in this case as a $20 difference is too high a price hike. This 1958 ad shows only a $10 price difference for the "Royal Clipper" gold plate on expansion band and on leather. Taking this into account, there must be some other factor apart from the mount involved and it is probably the adjustments. Below that we have a 1957 ad for the "Automatic" with 23 jewels, and the price difference on expansion and leather bands is $12, big rise in price to $20 with the subject watch, taking the dollar value at the time into the equation.

HE "C".

Bobbee what $20 difference are you talking about?  
$20 difference in relation to subject watch? We have no idea which of the two possible prices the subject watch originally sold for (C price vs EW price).  Are you basing your distinction between C and EW on an unknown original sales price?
or  $20 in relationship to your points about these various price differences in general?  :)  

Yes your price difference argument is sound in general, and I agree w/ the points you make about these various differences, but I'm missing how this relates to calling subject a "C" vs an "EW"?  Now if we had a hang tag, receipt or the likes (or an original band) we could say more about subject watch original price -but then we wouldn't be having this model variant discussion.  I like the discussions because lots of good stuff comes up- like the price differences and type of gold bands etc..... 

The $20 difference is the price difference between the "C" and the "EW", as discussed on the previous page in this thread, Will.

Here is another possible explanation. The ad referred to on the previous page has two different models with higher prices with the wording "natural gold" in their descriptions, the "C" and the "HW" HE's. Could it be possible that they are both solid gold?

Several of these watches have different designation letters in different ads. 

In the ads below the "EW" is the "A" on the next ad, and the "HW" becomes the "M".

Now what, drop the designation as Geoff says? This is becoming too complicated.

Bulova could hike prices or lower them as much as they pleased, why does it have to based on the value of anything?

The ad above states:

23 working Jewels...precision adjusted...waterproof...shock-resisIant

...lifetime unbreakable mainspring, in all models of 'HIS EXCELLENCY'.

all being the key word Gentlemen. Remove the mount from the Watch and they are essentially the same. Based on the conflicting ad I agree with Mr Baker.

'HIS EXCELLENCY'