Septimius Severus, imitations

There are several types of imitations
1) good silver (These are very rare)
2) base silver, but silver throughout (also rare)
3) fourrees, struck over base-metal flans wrapped with silver foil. These are common, but less common than the gray-metal and copper imitations.
4) lightly silvered -- in my opinion, these may use the technology of the surface-silvered coins of Probus and Aurelian
5) gray metal, cast and therefore in official style. Were these ever silvered?
6) copper, cast and therefore in official style. Are these cores? Were these ever silvered?

Spectacular pure silver imitation. Very rare.
SEVERVS PIVS AVG, laureate head right
/MONETA AVGG, Moneta seated left holding balance and cornucopiae
Reference: BMC p.227 #12 in "Appendix of doubtful hybrids" cited from L. A. Lawrence collection.
RIC 163 reverse.
ex Harlan J. Berk, sold by Curtis Clay, a top expert on Septimius Severus.

Base silver, not a fourre. The discoloration is dirt on top of the surface. Weak strike.
The letter-like forms are quite illegible, but suggest, on the reverse, possibly MONETA AVGG.
From a Bulgarian dealer, so possibly from that region.

imitation: AR18-17. 11:30. 3.16 grams.                                                             Prototype: AR18. 12:00. 3.41 grams
Crude style, but (fairly) good silver. This is not a silver-plated coin.
    [S]EVERVS - PIVS AVG, laureate head right
    Reverse legend retrograde! Forward, it would read: PART MAX PM T[RP VIIII] as on the illustrated prototype
Prototype: Sear 2.6323. RIC 176 page 114 (ends TRP VIIII). BMC (S&C) 385, page 232, plate 37.9 (TRP X).

Septimius Severus obverse combined with a Caracalla reverse.
18-17 mm. 2.61 grams (light, but not too obvious).
SEVERVS PIVS AVG, laureate head right
PART MAX PONT TRP IIII, trophy with two captives
The obverse legend of Severus belongs to 201-210, but without this reverse type, and the TRP IIII belongs to this reverse for Caracalla in year 201 (RIC 54, BMC page 45 double dagger footnote). The combination of two sides that do not belong together is called a hybrid (or a mule). Fourrés are often hybrids. Counterfeiters had little incentive to make sure the sides were paired in the official manner.

Excellent British fourree. Plating nearly intact.
SEPT SEV PERT AVG IMP, laureate head right
TRP VIVIM P VI COS IIII P 9approximately)
Prototype: BM --, but cf. #140, page 382 w. TRPVIVIIMPIICOSIIII in similar style and very similar reverse type, noted at plated, under "Septimius, Caracalla, and Geta, barbarous and irregular."

Some silver left on the obverse, but toned, and almost none left on the reverse.
IMP CASE L SEP SEV....COS II
/....VIII COS II ...., female standing left, holding patera
Obverse legend of AD 194 from an Eastern mint, but reverse date of 200.

Imitation with a thin surface-silvering, much like that seen on coins of Probus and Aurelian. Did the counterfeiters discover the technology first?
L SEPT SEV AVG IMP XI PART MAX, laureate head right
/COS II PP, Vicotry advancing left with wreath and palm.
Prototype: BMC (S&C) 655-6 [not illustrated, 3.60 and 2.78 grams] p. 286. #657-9, plate 44.4 has COS III (3.54 grams, with others down to 2.45)

gray metal. Cast - edge seem visible from side. Rough surrface.
SEVERVS PIVS AVG, laureate head right
/PM TRP XV - COS III PP, Winged Victory right, naked to waist, writing on round shield, set on palm tree, left foot on helmet.
Prototype: BMC 536, p. 263 (AD 207) plate 41.13. RIC 211, p. 118, plate 6.18 "C". Hill 915, p. 25 "C2" (Victory in Africa).

Coppery. No sign of silver, but a nice cast. Parts of the edge join are visible from the side.
SEVERVS PIVS AVG, laureate head right
/PM TRP XIII COS III PP, Jupiter standing let, holding thunderbolt and staff, eagle at feet left
Prototype: old Sear 1774. RIC 196 p. 117 "C". BMC 473 p. 250 plate 39.17. Hill 719 "AD 205"

Black and tan. I suppose this could just be tarnished official piece, but the wreath looks too large and Victory's robes flow dramatically.
[L SEPT] SEV PERT - AVG IMP [...]
[..]VG-G - COS I[...], Victory left holding large wreath and palm.
Prototype: see BMC plate 43.12 "VICT AVG-G-COS II PP" by deduction from Seaby RSC 694 photo.
Possibly IMP XI from Eastern mint, AD 198.
RIC page 103ff, #1200, p. 105.

Patinated, with encrustations on the obverse.
SEVERVS PIVS AVG
/VOTA SUSCEPTA XX, Severus sacrificing over tripod altar
Prototype: old Sear 1698v., RIC 308. BMC 375, plate 37.2, page 224 "AD 208".

                       prototype AR18. 12:00                                                                imitation. 17 mm. 12:00. 2.31 grams.
Official issue.                                                                                                    coppery bumps on dark low-base metal, in official style
SEVERVS PIVS AVG
    /INDVLGENTIA AVGG, in exergue: IN CARTH
    /Dea Caleestis riding right on lion, holding sceptre in left and thunderbolt in right
    /water gushes from a rock on the left and flows below to the right
Prototype: old Sear 1756. BMC 335-8, plate 35.11 and 35.14, page 218. RIC 266D, page 125, plate 7.9.