The idea is to click on a link.

I am looking at M1897 type Helmets. The development of Pickelhaube over time is in another section. The identification guide below is just a broad generalization.  One thing that makes this hobby so much fun is that it has so many nuances. The following two officer examples are samples only.  A helmet with a spike and one with a ball. There are MANY variations on a theme.  I'm just building a generalization out of popular demand. 

Infantry Officer

Artillery Officer

Cockade 

There are many color charts of landes cockades.  This is just one. I have an entire article on the so called "NCO  Cockade" at http://www.pickelhauben.net/articles/The%20NCO%20Cockade%20article.htm. There were two styles of cockades. Serrated and Non-serrated.  Sometimes the serrated types are called M15 cockades because some states (like Baden) Switched from non-serrated to serrated in 1915. This does not mean that the helmet has any other M15 features. Serrated cockades were multi piece and had a ring.  Non-serrated types were made from one piece.

Serrated (pointy things all around)

Non serrated

Within the two styles there were differences in the size of the hole. "Big Hole" handled M91 posts and small holes were for split brad rosettes.  Most officer cockades had small holes. Large hole versions were wartime only and their helmets called M15 style officer helmets. 

Chin Scales

Two basic styles convex and flat.  Sometimes it is REAL hard to tell. Therefore I rely on the rosettes to tell me. Chin scales were made by alternating 2 and 3 finger links with a leather strap on the inside.  The chin scales fastened in the front and there was a buckle on the leather. Chin scales were capped by the rosettes. Width of scales 13mm in front and 23mm in back by the rosette for flat scales.  Width of scales 14mm in front and 26mm in back by the rosette for convex scales. If no rosette you have an OR set of chin scales to fit the M91 post like the one below.

Kügel 

All balls are not equal.  Similar to spikes they ranged greatly in size. The official regulation size was 4.5 CM but like spikes no one listened to the regulation.  The biggest difference in balls, spikes, and trichters is thread match. There are at least three different thread sizes. Tops and bottoms had to match and the DOV catalog warned buyers that spike base had to be provided if they didn't make the helmet if you wanted a ball or trichter.

M15 helmets had Kügels also.

Last 2 pictures from the Bellars collection.

Pearl Ring

There are two kinds of pearl rings.  Old style which were discontinued officially for many units in the 1895 pattern OR helmet. OR pickelhauben are often called "NCO pearl rings" in error. Every OR had them up until 1887 and some unit types retained the old style pearl ring right to the end. It is possibly an NCO but more probably an OR. If you have a 48mm cockade with a silver ring it could well be a Feldwebel.  The Officer or private purchase pearl ring was the egg and dart variety. 

Officer

Old Style

Rear Spine

Supposedly 430mm long and 14 mm wide. There is a ridge around the edge of the spine. Hessian spines have to lug nuts on them similar to Dragoon enlisted spines.

Rosette

There are two basic types and they hold the key to determining if chin scales are curved (convex) or flat. Diameter supposedly 25mm.  Round Rosettes are for flat chin scales and oval ones are for convex chin scales. Diameter supposedly 27mm. 

There are also some specialty Rosettes used in Grenadier units. Also, during the war, More Officers used M91 type side lugs for their helmets and leather chin straps in the field. When chin scales were put on Officers used fake rosettes on top of the chin scales so you couldn't tell they were M91 posts beneath. However they had the three dots that enlisted M 91 chin scales had.

Shell or Corpus 

The helmets were, by regulation, supposed to be 1050 mm-1250mm high.

Spike

All Spikes are not equal.  They ranged greatly in size. The official regulation size was 80mm but no one listened to the regulation and the size of spikes in my collection rnge up to 130mm.  The biggest difference in balls, spikes, and trichters is thread match. There are at least three different thread sizes. Tops and bottoms had to match and the DOV catalog warned buyers that spike base had to be provided if they didn't make the helmet if you wanted a ball or trichter. Notice the two rings at the base of the spike on the left. This is an officer standard for round spikes.  Lack of these rings means not commissioned. There were also different types of fluted spikes.  The one on the right is fluted.

A spike could unscrew to allow a parade trichter to be added. Not all regiments had the option of such a trichter. Aprivately purchased helmet that unscrewed even though that Regiment was not allowed a trichter is normal. Having a screw spike was an option that was frequently purchased for the purpose of transport.

Bellars collection

Comparing fluted spikes is useful. Prussian general's helmets had two steps on the bottom of the flute and sat on top of the base. Bavarian style flutes, also used in Mecklenburg had three steps.

Hessian helmets had a platform and the picture below compares enlisted spikes with an officer spike.

Spike Base

There are multiple types of these.  The two basic styles are round plates and cruciform bases. Round bases are simple.  Round with four star studs attaching the helmet to the shell. Cruciform bases have two different styles based around the front leg.  Hessian cruciform bases have equal length legs. Bavarian Cruciform bases have a shorter front leg.  Long legs 70mm short leg 40 mm. 

Round

Cruciform

Bellars collection

Star Studs 

There are two sizes. I would call them normal and big.  There are very few big ones. I don't know the reasoning yet but Generals had them. Those not commissioned normally had "dome studs" in place of the star studs. Fähnrich often used dome studs as a way of marking their helmets as "not quite officer yet.)

Normal Officer

Dome studs on a Fähnrich helmet.  Note the Officer style pearl ring. 

Most Hessian Officer helmets used dome studs as in this M15 example.

Bellars collection

Vent Holes

There were no vents in the rear spine of the officer helmet.

Visor 

The brass colored trim is supposed to be between 380-400 mm wide and 6mm thick for officer helmets. 

Visor Studs

Wappen (Helmet Plate)

Lots of wappen obviously.  Below is a short diagram of different types.  In General Officer Wappen are "pierced" That means the crown on the eagle is voided and has holes in it. There are exceptions like Mecklenburg-Strelitz but it is a rule of thumb.  A Voided crown does not mean commissioned officer. It means privately purchased higher quality plate.