Pressing plants typically don't cut vinyl themselves. Cutting is performed by specialised studios. Some companies which cut Nirvana records are mentioned below.
Abbey Road Studios in London, UK, cut all of Simply Vinyl's releases up until late 2000. At this time the EMI plant which pressed those records changed owners and name, and Simply Vinyl then moved their vinyl production to Record Industry in Holland, to, among others, press the second pressings of their Nirvana releases.  Abbey Road was and is owned by EMI , and was the main mastering studio used by the EMI plant .
The studio cannot be identified by the matrix codes, as like most British mastering studios they only write the catalog numbers and side information around the outer edge of the lacquers or copper mothers to keep track of them before plating, when this area is trimmed off . The matrix codes were written or stamped into the run-out grooves by the pressing plants.
It was previously reported by this website that Abbey Road cut the Geffen vinyl releases in the early 1990's, but this seems to not be the case. They were cut by Copymasters and perhaps also by Transfermation (see below), and pressed by EMI.
Copymasters, known as Masterpiece since 1994/ 1995, is a mastering company based in London, UK. Like most British mastering studios they only write the catalog numbers and side information around the outer edge of the lacquers or copper mothers to keep track of them before plating, when this area is trimmed off . The actual matrix codes were written or stamped into the run-out grooves on the masters by the pressing plants prior to plating. They can only be identified from the matrix codes if the company or a mastering engineer signed the cut.
They cut several, if not all, of Geffen's British vinyl releases in the early 1990's, but they can only be indirectly identified by the signature of Stuart Hawkes, "Stu.", which appears on all the various Come As You Are cuts. Hawkes worked there from around 1989/ 1990 to 1996.
The black records were pressed by EMI , while the colored pressings and picture discs were pressed by Orlake as seen in the matrix codes. Matrix code examples of the Come As You Are black 12" and picture disc records, respectively, are shown on those two pages, both with Hawkes' signature, but very different matrix codes written by the two plants.
John Golden started his own mastering company in Ventura, CA, USA in 1993, after working for K Disc . The records mastered by Golden Mastering, by John himself or his son who joined him in 1998, are identified by handwritten or stamped "GOLDEN" in the matrix code.
Heathmans in London, UK went out of business in late 2008. They cut the 11 track reissues of Bleach (9878400341) which were pressed on white and clear vinyl in 2002 and 2006, respectively, and probably also the 13 track reissue which preceeded them. Images 1-2 show the sleeve and labels of a double sided lacquer from the 2002 mastering session. Double sided lacquers cannot be electroplated, so this was probably a reference cut done on a lathe in tandem with the lathe cutting the pair of lacquers for electroplating. The bright spots on the labels show where the second hole is, to keep the record from spinning while being cut. It has no matrix codes.
Like most British mastering studios, they only wrote the catalog numbers and side information around the outer edge of the lacquers to keep track of them before plating, when this area is trimmed off . The matrix codes were written or stamped into the run-out grooves by the pressing plants. Heathmans can only be identified if a mastering engineer signed the cut. One of the Bleach cuts which was pressed on both white and clear vinyl seems to have the signature of mastering engineer Jack Adams, "JA", who worked for Heathmans from 1999 to 2004 [7a].
The various Bleach reissues, except the 2010 pressing on black vinyl, were pressed by Orlake, identified by "OR" in the matrix code, as well as the overall handwritten style.
1. Bleach reference cut, sleeve front and back
2. Bleach reference cut, labels
K Disc mastered most of Sub Pop's releases before they went out of business in January 1995. Easily identified by handwritten or stamped "kdisc" in the matrix code, often along with the signature of the mastering engineer, "JG" - John Golden, or "ch" - Carol Hibbs. 
The New York City-based mastering company signed the matrix codes with "MASTERDISK" (stamped) or "MASTERDISK N.Y.C." (handwritten). Howie Weinberg's signature "Hw" is also found on some Nirvana records. Matrix codes for a set of lacquers or copper mothers cut by Masterdisk may be as this (Incesticide DGC-24504):
The catalog number is followed by the pressing plant code for the pressing plant they sent the lacquers to. "GL-1" then means it is the first set of lacquers or copper mothers they sent to the MCA plant in Gloversville. They also mastered several Nirvana records for Specialty Records Corporation, those are coded "SR-1", etc.
Hollywood-based mastering company. The only known Nirvana record they cut is the American clear In Utero LP. They signed their lacquers "TML" (stamped), followed by "-M", "-S", or "-X". The letters refer to the lathe used for cutting. They would often use two or three lathes in tandem, to make several lacquers at the same time. M is for the Scully master lathe, S for the Scully slave lathe, and X for the Neumann slave lathe. A slave lathe means that it is controlled by the master lathe. This means that they are from the same cut, but there may be small differences depending on the lathes. Typically the S lacquers resulted in the the quietest pressing because that lathe had a double belt insulated drive. 
This German company only cut the red Heart-Shaded Box 7" (GES19191). It was cut with direct metal mastering (DMM), and signed by the founder of the company, Günter Pauler .
Based in Frankfurt, Germany , this company mastered only the white Unplugged in New York LP (GEF 24727). They only wrote the catalog number, side A/B, and signed "SST".
Transfermation Mastering is a mastering company based in London, UK. Like most British mastering studios they only write the catalog numbers and side information around the outer edge of the lacquers or copper mothers to keep track of them before plating, when this area is trimmed off . The actual matrix codes were written or stamped into the run-out grooves on the masters by the pressing plants prior to plating.
Transfermation may have cut some of the Nirvana singles for Geffen UK in the early 1990's along with Copymasters, but it is not confirmed. The only confirmed cut is a set of Incesticide lacquers, shown in image 3. The record was not manufactured in the UK, so it is unsure why this cut was made.
3. Unreleased Incesticide lacquers, labels
Utopia was an independent mastering studio in London, UK . Their name only appears in the Sliver 12" (TUPEP 25) matrix, and indirectly in the 7" (TUP25) matrix as it is signed by Noel Summerville, "NS", who worked there for about a year during 1989-1990 [7b], but they probably cut all the Nirvana releases on Tupelo. Summerville also recalls cutting Bleach (TUPLP 6), but did not sign the cut . Except for the company name and signatures, like most British mastering studios they wrote the catalog numbers and side information around the outer edge of the lacquers only to keep track of which lacquer was which before plating. This area is trimmed off before plating.  The matrix codes were written into the run-out grooves by the processing/ pressing plant, which in the case of all the Nirvana records was MPO.