Thanks so much, that's just what I needed to see.
There's actually a fifth piece, the teapot, listed as part of (1) which you omitted. No problem, I'll assume it has the same mark as the others, and appraise accordingly (no photo needed unless it has a different mark).
Each of these pieces is marked with what's called the Belleek "3rd Green Mark" which means they date to the period 1965 - 1981 and as such are classified as "vintage Belleek" (as distinct from 'antique Belleek' and 'contemporary Belleek') for the purposes of valuation.
The following are the values you'd expect to get if you were to sell at a good antique auction house, or on an online auction site such as eBay, etc
(a) Coffee pot, "Limpet" embossed form (note the limpet shell on the elbow of the spout), lustre glazed with coral handle & finial in "cobb lustre" glaze. 3rd green mark (1965 - 1981).
Auction value: $60 - $125.
Retail/replacement/insurance value: $250.
(b) Milk pitcher, "Limpet" embossed form. Carinated shape, coral handle, lustre glaze. 3rd Green mark (1965 - 1981).
Auction value: $30 - $60.
Retail/replacement/insurance value: $120.
(c) Creamer & Sugar, "Neptune" embossed form, each with a pair of periwinkle shell feet. 3rd Green mark (1965 - 1981).
Auction value: $25 - $50 (for the pair)
Retail/replacement/insurance value: $100.
(d) Teapot, "Tridacna" (clam shell) embossed form . Coral handle with bifurcated top terminal and coral finial on cover. 3rd Green mark (1965 - 1981).
Auction value: $80 - $150.
Retail/replacement/insurance value: $300.
Hope this helps!
If you are happy with this so far, please go ahead and close this out by rating my answer (with the smiley faces or the 'accept' button) and initiate another question with: "For Robert S. appraisal of Belleek part (2)" in the subject line (or words to that effect) and attach a photo of all the bottoms of those marked (2) and we'll go from there.