diff --git a/spec/System/TestGemSocketQuality_spec.lua b/spec/System/TestGemSocketQuality_spec.lua
index 719004b176..09fb190321 100644
--- a/spec/System/TestGemSocketQuality_spec.lua
+++ b/spec/System/TestGemSocketQuality_spec.lua
@@ -101,6 +101,31 @@ describe("TestGemSocketQuality", function()
 		assert.are.equals(0, build.calcsTab.mainOutput.GemQuality)
 	end)
 
+	it("uses replacement item socket colours in item comparisons", function()
+		equipBody("R-R-R")
+		build.skillsTab:PasteSocketGroup("Slot: Body Armour\nFireball 20/0  1\nControlled Destruction 20/0  1\n")
+		runCallback("OnFrame")
+		assert.are.equals(0, build.calcsTab.mainOutput.GemQuality)
+		local baseDPS = build.calcsTab.mainOutput.CombinedDPS
+
+		build.itemsTab:CreateDisplayItemFromRaw(
+			"Rarity: RARE\nReplacement Robe\nSage's Robe\nQuality: 0\nSockets: B-B-B\nImplicits: 0\n")
+		local replacement = build.itemsTab.displayItem
+		build.itemsTab:AddDisplayItem(true)
+		runCallback("OnFrame")
+
+		local calcFunc = build.calcsTab:GetMiscCalculator()
+		local preview = calcFunc({ repSlotName = "Body Armour", repItem = replacement })
+		assert.are.equals(10, preview.GemQuality)
+		assert.is_true(preview.CombinedDPS > baseDPS)
+
+		build.itemsTab.slots["Body Armour"]:SetSelItemId(replacement.id)
+		build.buildFlag = true
+		runCallback("OnFrame")
+		assert.are.equals(preview.GemQuality, build.calcsTab.mainOutput.GemQuality)
+		assert.are.equals(preview.CombinedDPS, build.calcsTab.mainOutput.CombinedDPS)
+	end)
+
 	it("always grants the bonus with Dialla's 'always matches' mod", function()
 		-- Blue gem in a red socket
 		equipBody("R-R-R", "Gems Socketed always have the Quality bonus from Socket Colour\n")
diff --git a/src/Modules/CalcActiveSkill.lua b/src/Modules/CalcActiveSkill.lua
index de16231644..ce513c7154 100644
--- a/src/Modules/CalcActiveSkill.lua
+++ b/src/Modules/CalcActiveSkill.lua
@@ -552,9 +552,8 @@ function calcs.buildActiveSkillModList(env, activeSkill)
 	skillModList:NewMod("GemLevel", "BASE", activeSkill.activeEffect.srcInstance and activeSkill.activeEffect.srcInstance.level or activeSkill.activeEffect.level, "Max Level")
 	skillModList:NewMod("GemQuality", "BASE", activeSkill.activeEffect.srcInstance and activeSkill.activeEffect.srcInstance.quality or activeSkill.activeEffect.quality, "Max Quality")
 	-- matching socket bonus
-	local socketMatches = activeSkill.activeEffect.srcInstance and activeSkill.activeEffect.srcInstance.matchesSocket or activeSkill.activeEffect.matchesSocket
-	if socketMatches then
-		skillModList:NewMod("GemSocketQuality", "BASE", data.misc.MatchingSocketQualityBonus, "Socket Quality")
+	if (activeSkill.activeEffect.socketQuality or 0) > 0 then
+		skillModList:NewMod("GemSocketQuality", "BASE", activeSkill.activeEffect.socketQuality, "Socket Quality")
 	end
 	for _, supportProperty in ipairs(skillModList:Tabulate("LIST", activeSkill.skillCfg, "SupportedGemProperty")) do
 		local value = supportProperty.value
diff --git a/src/Modules/CalcSetup.lua b/src/Modules/CalcSetup.lua
index 7030116836..b4fc8affca 100644
--- a/src/Modules/CalcSetup.lua
+++ b/src/Modules/CalcSetup.lua
@@ -14,6 +14,21 @@ local m_min = math.min
 local m_max = math.max
 
 local tempTable1 = { }
+local gemSocketColours = { "R", "G", "B" }
+
+local function getMatchingSocketQuality(env, groupCfg, gemInstance, socketIndex)
+	local item = groupCfg.slotName and env.player.itemList[groupCfg.slotName]
+	local sockets = item and item.sockets
+	if not sockets then
+		return 0
+	elseif sockets.colourAlwaysMatches then
+		return data.misc.MatchingSocketQualityBonus
+	end
+	local grantedEffect = gemInstance.grantedEffect or (gemInstance.gemData and gemInstance.gemData.grantedEffect)
+	local gemColour = grantedEffect and grantedEffect.color and gemSocketColours[grantedEffect.color]
+	local socket = socketIndex and sockets[socketIndex]
+	return gemColour and socket and socket.color == gemColour and data.misc.MatchingSocketQualityBonus or 0
+end
 
 -- Initialise modifier database with stats and conditions common to all actors
 function calcs.initModDB(env, modDB)
@@ -1600,6 +1615,17 @@ function calcs.initEnv(build, mode, override, specEnv)
 		local supportLists = { }
 		local groupCfgList = { }
 		local processedSockets = {}
+		local socketIndexByGem = {}
+		local slotSocketedCounts = {}
+		for _, group in ipairs(build.skillsTab.socketGroupList) do
+			if group.slot then
+				local socketOffset = slotSocketedCounts[group.slot] or 0
+				for gemIndex, gemInstance in ipairs(group.gemList) do
+					socketIndexByGem[gemInstance] = socketOffset + gemIndex
+				end
+				slotSocketedCounts[group.slot] = socketOffset + #group.gemList
+			end
+		end
 		-- Process support gems adding them to applicable support lists
 		for index, group in ipairs(build.skillsTab.socketGroupList) do
 			local slot = group.slot and build.itemsTab.slots[group.slot]
@@ -1677,7 +1703,8 @@ function calcs.initEnv(build, mode, override, specEnv)
 							if not grantedEffect or not grantedEffect.support then
 								return
 							end
-							local actualQuality = gemInstance.quality + (gemInstance.matchesSocket and data.misc.MatchingSocketQualityBonus or 0)
+							local socketQuality = getMatchingSocketQuality(env, groupCfg, gemInstance, socketIndexByGem[gemInstance])
+							local actualQuality = gemInstance.quality + socketQuality
 							local supportEffect = {
 								grantedEffect = grantedEffect,
 								level = gemInstance.level,
@@ -1685,7 +1712,7 @@ function calcs.initEnv(build, mode, override, specEnv)
 								globalQuality = 0,
 								itemQuality = 0,
 								supportQuality = 0,
-								socketQuality = gemInstance.matchesSocket and data.misc.MatchingSocketQualityBonus or 0,
+								socketQuality = socketQuality,
 								srcInstance = gemInstance,
 								gemData = gemInstance.gemData,
 								superseded = false,
@@ -1754,7 +1781,8 @@ function calcs.initEnv(build, mode, override, specEnv)
 						for index, grantedEffect in ipairs(grantedEffectList) do
 							if not grantedEffect.support and not grantedEffect.unsupported and (not grantedEffect.hasGlobalEffect or gemInstance["enableGlobal"..index]) then
 								slotHasActiveSkill = true
-								local actualQuality = gemInstance.quality + (gemInstance.matchesSocket and data.misc.MatchingSocketQualityBonus or 0)
+								local socketQuality = getMatchingSocketQuality(env, groupCfg, gemInstance, socketIndexByGem[gemInstance])
+								local actualQuality = gemInstance.quality + socketQuality
 								local activeEffect = {
 									grantedEffect = grantedEffect,
 									level = gemInstance.level,
@@ -1762,7 +1790,7 @@ function calcs.initEnv(build, mode, override, specEnv)
 									globalQuality = 0,
 									itemQuality = 0,
 									supportQuality = 0,
-									socketQuality = gemInstance.matchesSocket and data.misc.MatchingSocketQualityBonus or 0,
+									socketQuality = socketQuality,
 									srcInstance = gemInstance,
 									gemData = gemInstance.gemData,
 								}