Add colorized bookmarks based on book element, requires spells to be discovered. It can be turned off in the Client settings. Another tweak setting can make it depend on the Archivist's Eyeglass artefact

src/main/resources/assets/ebwizardry/lang/en_us.lang

@@ -524,6 +524,7 @@ item.ebwizardry\:charm_move_speed.name=Icarus Medallion
 item.ebwizardry\:charm_move_speed.desc=Move at near-full speed when casting spells
 item.ebwizardry\:charm_spell_discovery.name=Archivist's Eyeglass
 item.ebwizardry\:charm_spell_discovery.desc=Spell books found in chests are much more likely to be ones you have not yet discovered
+item.ebwizardry\:charm_spell_discovery.desc.color=When equipped, you can see the element of a known spell book by the color of its bookmark
 item.ebwizardry\:charm_auto_smelt.name=Metallurgist's Mark
 item.ebwizardry\:charm_auto_smelt.desc=Pocket furnace triggers automatically when bound to a wand on your hotbar
 item.ebwizardry\:charm_lava_walking.name=Nether Ice Core
@@ -1692,6 +1693,10 @@ config.ebwizardry.replace_vanilla_fall_damage=Replace Vanilla Fall Damage
 config.ebwizardry.replace_vanilla_fall_damage.tooltip=Whether to replace Minecraft's distance-based fall damage calculation with an equivalent, velocity-based one. This is done such that mobs in freefall will take exactly the same damage as normal, so it will not break falling-based mob farms. Disable this if you experience falling-related weirdness! If this is disabled, some spells revert to a more simplistic method of resetting the player's fall damage in certain cases.
 config.ebwizardry.replace_vanilla_fall_damage.true=Yes - it's parkour time
 config.ebwizardry.replace_vanilla_fall_damage.false=No - break my legs normally
+config.ebwizardry.spell_book_colors_require_charm=Spell Book Colors Require Archivist's Eyeglass
+config.ebwizardry.spell_book_colors_require_charm.tooltip=Whether to require the Archivist's Eyeglass charm artifact to see colored spell book bookmarks.
+config.ebwizardry.spell_book_colors_require_charm.true=Yes - I want to see the colours only if the charm is worn
+config.ebwizardry.spell_book_colors_require_charm.false=No - I want to see the colours all the time
 config.ebwizardry.blindness_tweak=Blindness Tweak
 config.ebwizardry.blindness_tweak.tooltip=Whether to tweak the blindness effect to reduce follow distance when used on non-players. This automatically disables itself in favour of Potion Core's implementation if installed.
 config.ebwizardry.mob_loot_table_whitelist=Mob Loot Table Whitelist

src/main/resources/assets/ebwizardry/models/item/spell_book.json

@@ -1,14 +1,17 @@
 {
-    "parent": "item/generated",
-    "textures": {
-        "layer0": "ebwizardry:items/spell_book"
-    },
+    "parent": "ebwizardry:item/spell_book_undiscovered",
     "overrides": [
         {
             "predicate": {
                 "festive": 1
             },
             "model": "ebwizardry:item/festive_spell_book"
+        },
+        {
+            "predicate": {
+                "ebwizardry:discovered": 1
+            },
+            "model": "ebwizardry:item/spell_book_discovered"
         }
     ]
 }

src/main/resources/assets/ebwizardry/models/item/spell_book_discovered.json

@@ -0,0 +1,7 @@
+{
+    "parent": "item/generated",
+    "textures": {
+        "layer0": "ebwizardry:items/spell_book",
+        "layer1": "ebwizardry:items/spell_book_overlay"
+    }
+}

src/main/resources/assets/ebwizardry/models/item/spell_book_undiscovered.json

@@ -0,0 +1,6 @@
+{
+    "parent": "item/generated",
+    "textures": {
+        "layer0": "ebwizardry:items/spell_book"
+    }
+}