sorry, can't help with maker on this one................... but, would suggest that Fred's description of the type of glass should be adopted, since this colour has nothing to do with malachite, and I'm very very sure nothing to do with slag glass either

More importantly though, I'm confused regarding the attached pix in Fred's reply, showing the candlestick and creamer - both unmarked - stated as being part of Heppell's Registrations from 24th November 1882.
They may well be pieces made by Heppell and I might have missed the point entirely, but looking at this factory's original sepia photographs, submitted to the Board of Trade on the above date and allocated Rd. Nos. 390584 - 86, the pieces in those original pix have very little similarity with this stick and creamer, other than the inclusion of a stylized dolphin somewhere in the design.
Heppell's own factory photos, sent to the Board of Trade and given these three Registration Nos. on 24/11/1882 agree exactly with shapes shown in Raymond Slack's book .......... Rd. 390584 is the covered butter shown left on page 105 - Rd. 390585 is the rather top heavy sugar bowl shown right on page 105 - and Rd. 390586 is the handled milk jug shown on page 104.
I've no idea why Slack omits the Rd. Nos. from his captions to these pix - they would have been useful additions.
I've no first hand knowledge of Slack's comment that "no pattern books or catalogues exist today from this firm (Heppell)............etc.", and their business lasted only from 1874 to 1884, when as we all now know Davidson purchased Heppell's extensive stock of moulds.
If you want to get some idea of the potential confusion regarding Davidson's output in the later years of the C19 - regarding their use of other factories moulds, especially perhaps Heppell's - read Raymond Slack's comments on page 85 of his book.
Davidson produced vast amounts of marbled glass, doubtless much of it from moulds they had acquired elsewhere, so the issue of who made what is not easy to unravel especially on pieces made from other people's moulds that didn't incorporate a trade mark. I could well have missed seeing some recent piece of information that confirms beyond doubt that this stick and creamer are definitely from Heppell, but I'm wondering if their connection with Rd. 390584 - 86 has been made solely on the basis that there's a dolphin lurking in them so by default they must be from Heppell.
Coming back to Slack - I notice he shows a picture of this stick on page 76, in black Vitro-Porcelain, (stated as unmarked), and he includes this in his chapter on Davidson. Perhaps even more telling is Slack's picture No. 54 on page 75 "a dolphin pedestal salt cellar" and with the same stylized dolphins as appear on the stick and creamer - this item he says is shown in a Davidson catalogue "and was probably made from moulds bought from Heppell - being famous for their fish designs".
Apparently Heppell produced only two opaque colours - Opal and "Brown Malachite", so any other colours which incorporate a trade mark, will have been made after 1884 by Davidson.
Unless I've missed something, then it seems difficult to make the jump from Heppell's photos for 390584 - 86 to this stick and creamer.
Sorry this is over-long - not easy to keep matters simple when faced with such an array of information.

Ref. 'English Pressed Glass 1830-1900' - Raymond Slack - 1987