diff --git a/src/main/java/io/weaviate/client6/v1/api/collections/VectorConfig.java b/src/main/java/io/weaviate/client6/v1/api/collections/VectorConfig.java
index ae13f70c..dffa7450 100644
--- a/src/main/java/io/weaviate/client6/v1/api/collections/VectorConfig.java
+++ b/src/main/java/io/weaviate/client6/v1/api/collections/VectorConfig.java
@@ -285,7 +285,7 @@ public void write(JsonWriter out, VectorConfig value) throws IOException {
           vectorizer.add(value._kind().jsonValue(), config);
           vectorIndex.getAsJsonObject().add("vectorizer", vectorizer);
 
-          if (value.quantization() != null) {
+          if (value.quantization() != null && !config.getAsJsonObject().get("quantization").isJsonNull()) {
             vectorIndex.getAsJsonObject()
                 .get("vectorIndexConfig").getAsJsonObject()
                 .add(value.quantization()._kind().jsonValue(), config.getAsJsonObject().remove("quantization"));
diff --git a/src/main/java/io/weaviate/client6/v1/api/collections/VectorIndex.java b/src/main/java/io/weaviate/client6/v1/api/collections/VectorIndex.java
index 51096f63..12d2e2a0 100644
--- a/src/main/java/io/weaviate/client6/v1/api/collections/VectorIndex.java
+++ b/src/main/java/io/weaviate/client6/v1/api/collections/VectorIndex.java
@@ -13,15 +13,17 @@
 import com.google.gson.stream.JsonReader;
 import com.google.gson.stream.JsonWriter;
 
+import io.weaviate.client6.v1.api.collections.vectorindex.Dynamic;
 import io.weaviate.client6.v1.api.collections.vectorindex.Flat;
 import io.weaviate.client6.v1.api.collections.vectorindex.Hnsw;
+import io.weaviate.client6.v1.internal.TaggedUnion;
 import io.weaviate.client6.v1.internal.json.JsonEnum;
 
-public interface VectorIndex {
+public interface VectorIndex extends TaggedUnion<VectorIndex.Kind, Object> {
   static final String DEFAULT_VECTOR_NAME = "default";
   static final VectorIndex DEFAULT_VECTOR_INDEX = Hnsw.of();
 
-  public enum Kind implements JsonEnum<Kind> {
+  enum Kind implements JsonEnum<Kind> {
     HNSW("hnsw"),
     FLAT("flat"),
     DYNAMIC("dynamic");
@@ -43,17 +45,37 @@ public static Kind valueOfJson(String jsonValue) {
     }
   }
 
-  VectorIndex.Kind _kind();
+  /** Is this vector index of type HNSW? */
+  default Hnsw isHnsw() {
+    return _as(VectorIndex.Kind.HNSW);
+  }
+
+  /** Get as {@link Hnsw} instance. */
+  default Hnsw asHnsw() {
+    return _as(VectorIndex.Kind.HNSW);
+  }
+
+  /** Is this vector index of type FLAT? */
+  default Flat isFlat() {
+    return _as(VectorIndex.Kind.FLAT);
+  }
+
+  /** Get as {@link Flat} instance. */
+  default Flat asFlat() {
+    return _as(VectorIndex.Kind.FLAT);
+  }
 
-  /** Returns the on-the-wire name of the vector index type. */
-  default String type() {
-    return _kind().jsonValue();
+  /** Is this vector index of type DYNAMIC? */
+  default Dynamic isDynamic() {
+    return _as(VectorIndex.Kind.DYNAMIC);
   }
 
-  /** Get the concrete vector index configuration object. */
-  Object config();
+  /** Get as {@link Dynamic} instance. */
+  default Dynamic asDynamic() {
+    return _as(VectorIndex.Kind.DYNAMIC);
+  }
 
-  public static enum CustomTypeAdapterFactory implements TypeAdapterFactory {
+  static enum CustomTypeAdapterFactory implements TypeAdapterFactory {
     INSTANCE;
 
     private static final EnumMap<VectorIndex.Kind, TypeAdapter<? extends VectorIndex>> readAdapters = new EnumMap<>(
@@ -66,6 +88,7 @@ private final void addAdapter(Gson gson, VectorIndex.Kind kind, Class<? extends
     private final void init(Gson gson) {
       addAdapter(gson, VectorIndex.Kind.HNSW, Hnsw.class);
       addAdapter(gson, VectorIndex.Kind.FLAT, Flat.class);
+      addAdapter(gson, VectorIndex.Kind.DYNAMIC, Dynamic.class);
     }
 
     @SuppressWarnings("unchecked")
@@ -90,7 +113,7 @@ public void write(JsonWriter out, VectorIndex value) throws IOException {
           out.value(value._kind().jsonValue());
 
           out.name("vectorIndexConfig");
-          var config = writeAdapter.toJsonTree((T) value.config());
+          var config = writeAdapter.toJsonTree((T) value._self());
           config.getAsJsonObject().remove("name");
           Streams.write(config, out);
 
diff --git a/src/main/java/io/weaviate/client6/v1/api/collections/vectorindex/Dynamic.java b/src/main/java/io/weaviate/client6/v1/api/collections/vectorindex/Dynamic.java
new file mode 100644
index 00000000..63d82267
--- /dev/null
+++ b/src/main/java/io/weaviate/client6/v1/api/collections/vectorindex/Dynamic.java
@@ -0,0 +1,120 @@
+package io.weaviate.client6.v1.api.collections.vectorindex;
+
+import java.io.IOException;
+import java.util.function.Function;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
+import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
+import com.google.gson.annotations.SerializedName;
+import com.google.gson.internal.Streams;
+import com.google.gson.reflect.TypeToken;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+
+import io.weaviate.client6.v1.api.collections.VectorIndex;
+import io.weaviate.client6.v1.internal.ObjectBuilder;
+
+public record Dynamic(
+    @SerializedName("hnsw") Hnsw hnsw,
+    @SerializedName("flat") Flat flat,
+    @SerializedName("threshold") Long threshold)
+    implements VectorIndex {
+
+  @Override
+  public VectorIndex.Kind _kind() {
+    return VectorIndex.Kind.DYNAMIC;
+  }
+
+  @Override
+  public Object _self() {
+    return this;
+  }
+
+  public static Dynamic of() {
+    return of(ObjectBuilder.identity());
+  }
+
+  public static Dynamic of(Function<Builder, ObjectBuilder<Dynamic>> fn) {
+    return fn.apply(new Builder()).build();
+  }
+
+  public Dynamic(Builder builder) {
+    this(
+        builder.hnsw,
+        builder.flat,
+        builder.threshold);
+  }
+
+  public static class Builder implements ObjectBuilder<Dynamic> {
+
+    private Hnsw hnsw;
+    private Flat flat;
+    private Long threshold;
+
+    public Builder hnsw(Hnsw hnsw) {
+      this.hnsw = hnsw;
+      return this;
+    }
+
+    public Builder flat(Flat flat) {
+      this.flat = flat;
+      return this;
+    }
+
+    public Builder threshold(long threshold) {
+      this.threshold = threshold;
+      return this;
+    }
+
+    @Override
+    public Dynamic build() {
+      return new Dynamic(this);
+    }
+  }
+
+  public static enum CustomTypeAdapterFactory implements TypeAdapterFactory {
+    INSTANCE;
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
+      var rawType = type.getRawType();
+      if (!Dynamic.class.isAssignableFrom(rawType)) {
+        return null;
+      }
+
+      final var hnswAdapter = gson.getDelegateAdapter(VectorIndex.CustomTypeAdapterFactory.INSTANCE,
+          TypeToken.get(Hnsw.class));
+      final var flatAdapter = gson.getDelegateAdapter(VectorIndex.CustomTypeAdapterFactory.INSTANCE,
+          TypeToken.get(Flat.class));
+
+      return (TypeAdapter<T>) new TypeAdapter<Dynamic>() {
+
+        @Override
+        public void write(JsonWriter out, Dynamic value) throws IOException {
+
+          var dynamic = new JsonObject();
+
+          dynamic.addProperty("threshold", value.threshold);
+          dynamic.add("hnsw", hnswAdapter.toJsonTree(value.hnsw));
+          dynamic.add("flat", flatAdapter.toJsonTree(value.flat));
+
+          Streams.write(dynamic, out);
+        }
+
+        @Override
+        public Dynamic read(JsonReader in) throws IOException {
+          var jsonObject = JsonParser.parseReader(in).getAsJsonObject();
+
+          var hnsw = hnswAdapter.fromJsonTree(jsonObject.get("hnsw"));
+          var flat = flatAdapter.fromJsonTree(jsonObject.get("flat"));
+          var threshold = jsonObject.get("threshold").getAsLong();
+          return new Dynamic(hnsw, flat, threshold);
+        }
+      }.nullSafe();
+    }
+  }
+}
diff --git a/src/main/java/io/weaviate/client6/v1/api/collections/vectorindex/Flat.java b/src/main/java/io/weaviate/client6/v1/api/collections/vectorindex/Flat.java
index 92069553..dfa1da18 100644
--- a/src/main/java/io/weaviate/client6/v1/api/collections/vectorindex/Flat.java
+++ b/src/main/java/io/weaviate/client6/v1/api/collections/vectorindex/Flat.java
@@ -16,7 +16,7 @@ public VectorIndex.Kind _kind() {
   }
 
   @Override
-  public Object config() {
+  public Object _self() {
     return this;
   }
 
diff --git a/src/main/java/io/weaviate/client6/v1/api/collections/vectorindex/Hnsw.java b/src/main/java/io/weaviate/client6/v1/api/collections/vectorindex/Hnsw.java
index 92e68424..a6e28ee7 100644
--- a/src/main/java/io/weaviate/client6/v1/api/collections/vectorindex/Hnsw.java
+++ b/src/main/java/io/weaviate/client6/v1/api/collections/vectorindex/Hnsw.java
@@ -29,7 +29,7 @@ public VectorIndex.Kind _kind() {
   }
 
   @Override
-  public Object config() {
+  public Object _self() {
     return this;
   }
 
diff --git a/src/main/java/io/weaviate/client6/v1/internal/json/JSON.java b/src/main/java/io/weaviate/client6/v1/internal/json/JSON.java
index 4bee47c6..d1dc1db5 100644
--- a/src/main/java/io/weaviate/client6/v1/internal/json/JSON.java
+++ b/src/main/java/io/weaviate/client6/v1/internal/json/JSON.java
@@ -28,8 +28,17 @@ public final class JSON {
         io.weaviate.client6.v1.api.collections.Vectors.CustomTypeAdapterFactory.INSTANCE);
     gsonBuilder.registerTypeAdapterFactory(
         io.weaviate.client6.v1.api.collections.VectorConfig.CustomTypeAdapterFactory.INSTANCE);
+
+    // These 2 adapters need to be registered in this exact order: Dynamic
+    // (narrower), VectorIndex (broader).
+    // When searching for an adapter, Gson will pick the first adapter factory that
+    // can process the class, and it's important that Dynamic.class is processed by
+    // this factory.
+    gsonBuilder.registerTypeAdapterFactory(
+        io.weaviate.client6.v1.api.collections.vectorindex.Dynamic.CustomTypeAdapterFactory.INSTANCE);
     gsonBuilder.registerTypeAdapterFactory(
         io.weaviate.client6.v1.api.collections.VectorIndex.CustomTypeAdapterFactory.INSTANCE);
+
     gsonBuilder.registerTypeAdapterFactory(
         io.weaviate.client6.v1.api.collections.Reranker.CustomTypeAdapterFactory.INSTANCE);
     gsonBuilder.registerTypeAdapterFactory(
diff --git a/src/test/java/io/weaviate/client6/v1/internal/json/JSONTest.java b/src/test/java/io/weaviate/client6/v1/internal/json/JSONTest.java
index f6f15e0d..f6e8d322 100644
--- a/src/test/java/io/weaviate/client6/v1/internal/json/JSONTest.java
+++ b/src/test/java/io/weaviate/client6/v1/internal/json/JSONTest.java
@@ -32,6 +32,7 @@
 import io.weaviate.client6.v1.api.collections.quantizers.PQ;
 import io.weaviate.client6.v1.api.collections.rerankers.CohereReranker;
 import io.weaviate.client6.v1.api.collections.vectorindex.Distance;
+import io.weaviate.client6.v1.api.collections.vectorindex.Dynamic;
 import io.weaviate.client6.v1.api.collections.vectorindex.Flat;
 import io.weaviate.client6.v1.api.collections.vectorindex.Hnsw;
 import io.weaviate.client6.v1.api.collections.vectorindex.MultiVector;
@@ -166,6 +167,28 @@ public static Object[][] testCases() {
                 }
                 """,
         },
+        {
+            VectorConfig.class,
+            SelfProvidedVectorizer.of(none -> none
+                .vectorIndex(Dynamic.of(idx -> idx
+                    .hnsw(Hnsw.of(hnsw -> hnsw
+                        .ef(1)
+                        .efConstruction(2)))
+                    .flat(Flat.of(flat -> flat
+                        .vectorCacheMaxObjects(100)))
+                    .threshold(5)))),
+            """
+                {
+                  "vectorIndexType": "dynamic",
+                  "vectorizer": {"none": {}},
+                  "vectorIndexConfig": {
+                    "flat": {"vectorCacheMaxObjects": 100},
+                    "hnsw": {"ef": 1, "efConstruction": 2},
+                    "threshold": 5
+                  }
+                }
+                """,
+        },
         {
             VectorConfig.class,
             SelfProvidedVectorizer.of(none -> none